This fixes compatibility with trigger request create service.

* master: (538 commits)
  Fix broken URI joining for `teamcity_url` with suffixes
  Factorize duplicated code into a method in BambooService and update specs
  Fix broken URI joining for `bamboo_url` with suffixes
  Honor credentials on calling Bamboo CI trigger
  Update CHANGELOG
  Use Issue.visible_to_user in Notes.search to avoid query duplication
  Project members with guest role can't access confidential issues
  Allow users to create confidential issues in private projects
  Update CHANGELOG
  Remove deprecated issues_tracker and issues_tracker_id from project
  Schema doesn’t reflect the changes of the last 3 migrations
  Apply reviewer notes: update CHANGELOG, adjust code formatting
  Move issue rendering tests into separate contexts
  Move change description to proper release and fix typo
  Add more information into RSS fead for issues
  Revert CHANGELOG
  Also rename "find" in the specs
  Change to new Notes styleguide
  Add guide on changing a document's location
  Change logs.md location in README
  ...

Conflicts:
	app/services/ci/create_builds_service.rb
	app/services/ci/create_pipeline_service.rb
	app/services/create_commit_builds_service.rb
	spec/models/ci/commit_spec.rb
	spec/services/ci/create_builds_service_spec.rb
	spec/services/create_commit_builds_service_spec.rb

Add whitelisted elements correctly in sanitization

Add whitelisted elements correctly in sanitization

Consider this command:

    bundle exec rails r "include GitlabMarkdownHelper
    puts markdown('<span>this is a span</span>', pipeline: :description)
    puts markdown('<span>this is a span</span>')"

And the same in the opposite order:

    bundle exec rails r "include GitlabMarkdownHelper
    puts markdown('<span>this is a span</span>')
    puts markdown('<span>this is a span</span>', pipeline: :description)"

Before this change, they would both output:

    <p><span>this is a span</span></p>
    <p>this is a span</p>

That's because `span` is added to the list of whitelisted elements in
the `SanitizationFilter`, but this method tries not to make the same
changes multiple times. Unfortunately,
`HTML::Pipeline::SanitizationFilter::LIMITED`, which is used by the
`DescriptionPipeline`, uses the same Ruby objects for all of its hash
values _except_ `:elements`.

That means that whichever of `DescriptionPipeline` and `GfmPipeline` is
called first would have `span` in its whitelisted elements, and the
second wouldn't.

Fix this by adding a special check for modifying `:elements` twice, then
checking `:transformers` as before.


See merge request !4588

Allow users to create confidential issues in private projects

Closes #14787

## What does this MR do?

Allow users to create confidential issues in private projects, and exclude access to them to project members with `Guest` role.

## Are there points in the code the reviewer needs to double check?

The query generated by the `User#authorized_projects` method.

## Why was this MR needed?

Community have been requesting this feature.

## What are the relevant issue numbers?

https://gitlab.com/gitlab-org/gitlab-ce/issues/14787

https://gitlab.com/gitlab-org/gitlab-ce/issues/3678

## Screenshots (if relevant)

Not relevant.

## Todo

- [x] Allow users to create confidential issues in private projects
- [x] Project members with `Guest` role should not have access to confidential issues
- [ ] ~~Apply changes in EE + Elasticsearch~~ Will be done in another MR, when this got merged

See merge request !3471

Bamboo & TeamCity Services: Fix missing credentials & URL handling

_Note: Originally opened at !4367 by @bentolor_

I've also fixed the URL handling for TeamCity which is very similar to Bamboo implementation-wise.

-----

*Note:* This is a port from my [original pull request on GitHub](https://github.com/gitlabhq/gitlabhq/pull/9428)

## What does this MR do?
This improves the Bamboo Service and provides two fixes:

1. One for the situation, where the build trigger won't work because Bamboo is requiring authentication credentials for the trigger GET: 8f25aca307b49ee006172b8c2985a878800aa6b6
2. One which fixes the way how the configured Bamboo base URL is assembled to the final REST URL. fe9eb30d7ebe4a83eefea7e06f8b69b135dad15d

### Regarding credentials
The change now does provide additional HTTP Basic Auth parameters if user credentials were provided and appends an request parameter indicating the HTTP Basic Authentication should be used. This aligns interaction with Bamboo with the other calls this service executes.

### Regarding URL handling
If one had configured a `bamboo_url` like http://foo.bar/bamboo in the previous implementation the plugin directed it's request i.e. to http://foo.bar/rest/... instead of http://foo.bar/bamboo/rest/...


## Are there points in the code the reviewer needs to double check?
The second issues was probably an unwanted side effect of how Ruby's `URI.join` is working. It will only work correctly, if 
- ... the prefix URL has at least one or more  trailing `/`
- .. the appendix parts are _not_ prefixed with `/`

I need try & figure it out using the rather lacking, official stdlib documentation and playing around in `irb`. As I'm an absolute Ruby novice I'm unable to add/provide new tests.

## Why was this MR needed?
Because Gitlab does not work in our Bamboo-Environment at all: Neither it is able to trigger Bamboo runs nor does the Merge status check work. This MR at least fixes the trigger issues.

## What are the relevant issue numbers?
This MR originates from my [original pull request on GitHub](https://github.com/gitlabhq/gitlabhq/pull/9428).
Sadly the issue, that the merge status is still not working correctly for branches will still not work. But at least the trigger works. 

There happened to be very much discussion about the branch status issue in #1355 and  #2562 though that one is lost as the author retracted his branch. 

See merge request !4408

Add more information into RSS feed for issues

## What does this MR do?

This MR adds issue text, labels , milestone, assignee and due date into issues RSS feed.

## Are there points in the code the reviewer needs to double check?

#14572 requests to add 'weight' among other fields. Seems like issue weight is available
in enterprise edition only so it is not implemented in this MR. Please correct me if I'm wrong.

## Why was this MR needed?

This MR is needed because it extends issues RSS feed with useful information requested in
#14572.

## What are the relevant issue numbers?

https://gitlab.com/gitlab-org/gitlab-ce/issues/14572

See merge request !4158

If one had configured a `teamcity_url` like http://foo.bar/teamcity in
the previous implementation the plugin directed it's request i.e. to
http://foo.bar/httpAuth/... instead of http://foo.bar/teamcity/httpAuth/...

`URI.join` only works correctly, if the prefix URL has
  - at least one or more  trailing '/'
  - the appended parts are _not_ prefixed with '/'

The current implementation should work with all sorts of TeamCity base
URLs.
Signed-off-by: NRémy Coutable <remy@rymai.me>

Signed-off-by: NRémy Coutable <remy@rymai.me>

If one had configured a `bamboo_url` like http://foo.bar/bamboo in the
previous implementation the plugin directed it's request i.e. to
http://foo.bar/rest/... instead of http://foo.bar/bamboo/rest/...

`URI.join` only works correctly, if the prefix URL has
  - at least one or more  trailing '/'
  - the appended parts are _not_ prefixed with '/'

The current implementation should work with all sorts of Bamboo base URLs.
Signed-off-by: NRémy Coutable <remy@rymai.me>

This improves the Bamboo Service and provides a fix for situations,
where the build trigger won't work, because Bamboo is requiring
authentication also for the trigger GET.

The change now does provide additional HTTP Basic Auth parameters
if user credentials were provided and appends an request parameter
indicating the HTTP Basic Authentication should be used.
This aligns interaction with Bamboo with the other calls this service
executes.
Signed-off-by: NRémy Coutable <remy@rymai.me>

Retry spinach tests in case of failure using rerun reporter

## What does this MR do?

Fixes Spinach tests to retry on tests on master


See merge request !4539

Remove deprecated issues_tracker and issues_tracker_id from project model

Closes #3941

See merge request !4603

Update schema.rb for most recent migrations

Fixes #18532

See merge request !4636

The schema doesn’t reflect the changes of the last 3 migrations:

* 20160610140403_remove_notification_setting_not_null_constraints.rb
* 20160610201627_migrate_users_notification_level.rb
* 20160610301627_remove_notification_level_from_users.rb

Remove counters from Pipeline navigation

* counters are heavy from UI perspective
* duplicates information from tabs below
* shows 0 for less active projects. Jumps from 0 to N constantly. 

I think we should render counters only when necessary and only for filters ( tabs on white bg ).  Exception:  issues, merge requests in top navigation as status of project popularity and action required from maintainers 


cc @grzesiek @ayufan @jschatz1 

See merge request !4617

Improve Gitlab::Auth method names

Auth.find was a very generic name for a very specific method.
Auth.find_in_gitlab_or_ldap was inaccurate in GitLab EE where it also
looks in Kerberos.


See merge request !4589

Enable Style/MultilineBlockChain rubocop style cop

Avoid multi-line chains of blocks.

See #17478.

See merge request !4349

Update brakeman from 3.2.1 to 3.3.2

Removes a few dependencies.

Changelog: https://github.com/presidentbeef/brakeman/blob/master/CHANGES

See merge request !4627

Fix typo causing related branches to Error 500

From Sentry: https://sentry.gitlap.com/gitlab/gitlabcom/issues/6154/

See merge request !4611

Fixes bulk-assign label for multiple issues not having the same labels

## What does this MR do?
Fixes a bug when bulk-assigning a label to multiple issues while the label is present in on the issues on the selection.

## Screenshots (if relevant)

**Before Bugfix**

<img src="/uploads/ad1f290bcf3930177a3a71c69cbe5325/before-bugfix.gif" width="700"/>

**After Bugfix**

<img src="/uploads/1f04d6bf027806fb13ca3773febda744/bugfix.gif" width="700"/>

## Does this MR meet the acceptance criteria?

- [x] Tests
  - [x] Added for this feature/bug
  - [x] All builds are passing
- [x] Branch has no merge conflicts with `master` (if you do - rebase it please)

See merge request !4602

Added when to artifacts

The syntax for this will be:

```
job:
  artifacts:
    when: on_failure
```

cc @grzesiek @tmaczukin 

Fixes https://gitlab.com/gitlab-org/gitlab-ce/issues/4034


See merge request !4201

Cache only apt and ruby from vendor

## What does this MR do?

Optimises caching mechanism when testing gitlab-ce/ee repositories.


See merge request !4619