Add more Slack notifications for issue and merge request events

From https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/237 by Stan Hu.

See merge request !1556

Web Hook sends email of pusher

See merge request !1630

Add Service Templates to CHANGELOG

See merge request !1633

Advise on how to help others.

See merge request !1632

Bump gitlab_git to rc15

For #2033

See merge request !1631

Add dashboard milestones.

Closes #1422.

![Screen_Shot_2015-03-03_at_16.20.36](https://dev.gitlab.org/gitlab/gitlabhq/uploads/795b480a2552e1d26436c3db2158cb81/Screen_Shot_2015-03-03_at_16.20.36.png)

See merge request !1621

Connect GitLab buttons doc

The "GitLab buttons in Gmail" documentation was not linked from anywhere else.

Instead of assuming that these docs are not current, or should not be accessible, I've linked to them from doc/integrations/README.md.

If linking is the less desirable approach, please advise.

See merge request !339

Merge branch 'connect_gitlab_buttons_doc' of gitlab.com:perforce/gitlab-ce into connect_gitlab_buttons_doc

else. It is now linked.

Autosave title and description of new issues/MRs.

Closes #2048.

See merge request !1595

Commits statistic grammar

Fixes #2089

Changed spelling from Commits statistic to Commit statistics

See merge request !1625

Changed to 'View Build Page'

Fixes #2093

Changes 'Build Page' to 'View build page'

See merge request !1626

Fix namespace in merge request url building

Changes in 42387b73 now require namespace specification and broke abc69c89.

There are additional helper functions in c530ca00, but this seemed easier not to rely on them.

See merge request !363

Fix server error when editing a note to "+1" or "-1"

### Summary

If a user edits a comment with "+1" or "-1" in the beginning, the POST returns an Internal Server error. (issue #1151). This merge request resolves that error.

### Steps to reproduce

1. Comment on an issue with "Test comment".
2. Edit the issue.
3. Write "+1" and click "Save Comment".

### Expected behavior

The edited note should be saved and refreshed. Any previous upvotes/downvotes from the user should contain a strikethrough.

### Observed behavior

Internal Error

### Relevant logs

```
Started PUT "/avocode/avocode-manager/notes/4996" for 185.33.136.107 at 2015-02-28 17:11:53 +0100
Processing by Projects::NotesController#update as JS
Parameters: {"utf8"=>"✓", "authenticity_token"=>"*removed*", "note"=>{"note"=>"+1\r\n\r\nYes"}, "commit"=>"Save Comment", "project_id"=>"avocode/avocode-manager", "id"=>"4996"}
Completed 500 Internal Server Error in 86ms
ActionView::Template::Error (undefined method `each' for nil:NilClass):
28: %span.note-last-update
29: = note_timestamp(note)
30:
31: - if note.superceded?(@notes)
32: - if note.upvote?
33: %span.vote.upvote.label.label-gray.strikethrough
34: %i.fa.fa-thumbs-up
app/models/note.rb:495:in `superceded?'
app/views/projects/notes/_note.html.haml:31:in `_app_views_projects_notes__note_html_haml___812277000516355462_69988235638820'
app/controllers/projects/notes_controller.rb:71:in `note_to_html'
app/controllers/projects/notes_controller.rb:103:in `render_note_json'
app/controllers/projects/notes_controller.rb:39:in `block (2 levels) in update'
app/controllers/projects/notes_controller.rb:38:in `update'
```

### Fix

It turns out no tests were present for the "Edit Issue" functionality. I added spinach tests to exercise this and reproduced the error.

Most of the routes in `notes_controller.rb` appear to render all notes for the given discussion. `_form.html.haml` needs the full list of notes commented by the user to add strikethroughs for older upvotes/downvotes. However, only the `index` route appeared to obtain this information. The fix is to add a `before_filter` to obtain all the user's notes beforehand, except in the delete case where this information is not needed.

Things to watch: `NotesFinder` needs `target_type` and `target_id` to determine what to do. I'm not sure if there is a conscious effort to phase these keywords out in favor of `noteable_type` and `noteable_id`.

See merge request !360

Don't leak information about private project existence via Git-over-SSH/HTTP.

Fixes #2040 and https://gitlab.com/gitlab-org/gitlab-ce/issues/343.

Both `Grack::Auth` (used by Git-over-HTTP) and `Api::Internal /allowed` (used by gitlab-shell/Git-over-SSH) now return a generic "Not Found" error when the project exists but the user doesn't have access to it.

See merge request !1578

Render go-import meta tag for private repos.

The previously solution (626f5bab) required a change to nginx config and broke visits from Googlebot and other clients including "go" in their user agent.

See merge request !1587

Clearly mark it as installation from source.

See merge request !1622

Don't show Unassigned in user select when searching.

Fixes #2056.

When a search term is present, the Unassigned item isn't rendered, so the highlighted item is the first search result and hitting Enter works as expected.

See merge request !1620

Fix import check for case sensetive namespaces

If you already have namespace `ABc` and you try to import project with namespace `abC` - import will fail with 422 error.

cc @valery

See merge request !1618

Count commits in branches as well in the commit calendar

This MR fixes a small bug in the commit calendar.
Currently only commits that are in the master branch are counted.
With this change, commits in other branches are included as well.

fixes one of the issues found in #1162

See merge request !362