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

    A lot of git operations were being repeated, for example, to build a url
    you would ask if the path was a Tree, which would call a recursive routine
    in Gitlab::Git::Tree#where, then ask if the path was a Blob, which would
    call a recursive routine at Gitlab::Git::Blob#find, making reference to
    the same git objects several times. Now we call Rugged::Tree#path, which
    allows us to determine the type of the path in one pass.

    Some other minor improvement added, like saving commonly used references
    instead of calculating them each time.

This reverts commit 3e991230.

# Conflicts:
#	app/models/project.rb

There are several changes to this module:

1. The use of an explicit stack in Participable#participants
2. Proc behaviour has been changed
3. Batch permissions checking

== Explicit Stack

Participable#participants no longer uses recursion to process "self" and
all child objects, instead it uses an Array and processes objects in
breadth-first order. This allows us to for example create a single
Gitlab::ReferenceExtractor instance and pass this to any Procs. Re-using
a ReferenceExtractor removes the need for running potentially many SQL
queries every time a Proc is called on a new object.

== Proc Behaviour Changed

Previously a Proc in Participable was expected to return an Array of
User instances. This has been changed and instead it's now expected that
a Proc modifies the Gitlab::ReferenceExtractor passed to it. The return
value of the Proc is ignored.

== Permissions Checking

The method Participable#participants uses
Ability.users_that_can_read_project to check if the returned users have
access to the project of "self" _without_ running multiple SQL queries
for every user.

Now there is a single source of information for which attribute a model
uses to be referenced, and its special character.

Signed-off-by: NJeroen van Baarsen <jeroenvanbaarsen@gmail.com>

for his work and help)

Signed-off-by: NDmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

Signed-off-by: NDmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

Add a note to merge requests and issues when they're mentioned by a
merge request, issue, or commit in another project.

Signed-off-by: NDmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

* project_with_code -> project
* project -> ermpty_project
Signed-off-by: NDmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

Any mention of Issues, MergeRequests, or Commits via GitLab-flavored markdown
references in descriptions, titles, or attached Notes creates a back-reference
Note that links to the original referencer. Furthermore, pushing commits with
commit messages that match a (configurable) regexp to a project's default
branch will close any issues mentioned by GFM in the matched closing phrase.
If accepting a merge request would close any Issues in this way, a banner is
appended to the merge request's main panel to indicate this.

The good:

 - You can do a merge request for a forked commit and it will merge properly (i.e. it does work).
 - Push events take into account merge requests on forked projects
 - Tests around merge_actions now present, spinach, and other rspec tests
 - Satellites now clean themselves up rather then recreate

The questionable:

 - Events only know about target projects
 - Project's merge requests only hold on to MR's where they are the target
 - All operations performed in the satellite

The bad:

  -  Duplication between project's repositories and satellites (e.g. commits_between)

(for reference: http://feedback.gitlab.com/forums/176466-general/suggestions/3456722-merge-requests-between-projects-repos)

Fixes:

Make test repos/satellites only create when needed
-Spinach/Rspec now only initialize test directory, and setup stubs (things that are relatively cheap)
-project_with_code, source_project_with_code, and target_project_with_code now create/destroy their repos individually
-fixed remote removal
-How to merge renders properly
-Update emails to show project/branches
-Edit MR doesn't set target branch
-Fix some failures on editing/creating merge requests, added a test
-Added back a test around merge request observer
-Clean up project_transfer_spec, Remove duplicate enable/disable observers
-Ensure satellite lock files are cleaned up, Attempted to add some testing around these as well
-Signifant speed ups for tests
-Update formatting ordering in notes_on_merge_requests
-Remove wiki schema update
Fixes for search/search results
-Search results was using by_project for a list of projects, updated this to use in_projects
-updated search results to reference the correct (target) project
-udpated search results to print both sides of the merge request

Change-Id: I19407990a0950945cc95d62089cbcc6262dab1a8

Also specify separate project factory for project with filled repo

Also, just for extra paranoia, only call safe_message once in the
decorator methods

Adds specs to make sure it still works