API: Implement edit via API for projects

I've picked up https://github.com/gitlabhq/gitlabhq/pull/8055 fixed the few hound warnings and replaced all double quotes in the spec file where possible.

# From the original PR:

Implements edit via API for projects. Edit was part of missing features in feature request Full CRUD operations via API for projects.
http://feedback.gitlab.com/forums/176466-general/suggestions/3904506-full-crud-operations-via-api-for-projects

Feature is implemented using existing UpdateService for projects. Permission to change visibility level and name are checked in addition to check for permission to administer project.

Doesn't allow updating project namespace id, because there was existing API-method for transferring project to a group.

Documentation added to doc/api/projects.md. Uses API request PUT /projects/:id .

Tests included for:
1. Success for changing path
2. Success for changing name
3. Success for changing visibility level
4. Success for changing all other attributes
5. Success for changing name & path to existing name & path but in different namespace
6. Failure if not authenticated
7. Failure if path exists in project's namespace
8. Failure if name exists in project's namespace
9. Failure if not sufficient permission to change name
10. Failure if not sufficient permission to change visibility level
11. Failure if not sufficient permission to change other attributes

Allows updating following parameters:

* name
* path
* visibility_level
* public
* default_branch
* issues_enabled
* wiki_enabled
* snippets_enabled
* merge_requests_enabled
* description

See merge request !310

Show modal window with instructions if GitHub integration disabled

See merge request !1424

Improve commit page

See merge request !1423

API: List issues for a particular milestone

# What does this MR do?
This MR adds a new API method for retrieving the issues associated with a particular milestone. The resource is described at ":id/milestones/:milestone_id/issues", returning a simple array of issues.

I've picked up gitlab-org/gitlab-ce!113  and fixed the test for it.
From the original MR:
This feature was motivated by an in-house project for reporting--for large projects, retrieving and filtering the entire issue list by milestone was becoming too slow, particularly when pagination required multiple requests. While this resource also uses pagination, it allows the consumer to limit reporting to the particular milestone they are interested in.

@dblessing Please take a look :)

See merge request !308

Conflicts:
	CHANGELOG

Upgrade to Sidekiq 3.3

Fixes #1807.  Upgrades Sidekiq to the latest stable release.

cc @sytse

See merge request !1419

The previous recommend incantation would leave the process we read from
hanging around, even though it had finished. That gives you a
'defunct'/'zombie' process.

Append in place for strings and arrays [failure unrelated]

Validation of 'Create branch' and 'Create tag' buttons

Fix various typos

Conflicts:
	CHANGELOG

Disable 'check all issues' checkbox for unprivileged users.

Fix spinner icon to match others

Fix sentence in notification page

Correct the sentence in profile notification settings page.

/cc @jacobvosmaer @dzaporozhets

See merge request !1421

Remove unnecessary / from avatar url

## What does this MR do?

This MR removes the unecessary / from the avatar url.

## What Use Case does this MR solve?

The // in the url cold lead to avatars not being displayed (reported on IRC)

With this MR the avatar url changes from
http://localhost:3000//uploads/user/avatar/1/gitlab_logo.png
to
http://localhost:3000/uploads/user/avatar/1/gitlab_logo.png

@dblessing Can you take a look?

See merge request !303

show diff in submodules

Allow commit messages to close several issues at once

Show tags in commit view

### What does this MR do?
With this MR you can see the assigned tags for a commit in the commit view.
### Are there points in the code the reviewer needs to double check?
I don't think so. But it would be awesome if the reviewer can tell me how to add a tag to the sample_commit in spec/support/repo_helpers.rb.
Then I can add a test for the new tag_names_contains method as soon as possible :)

### Why was this MR needed?
At the moment if one click on a commit will see details such as: parent commit, amount of additions, deletions, but will not see if this commit has Tag linked to it.
Showing branch, tag details will give better overview about the commit

### What are the relevant issue numbers / Feature requests?
Feature request: http://feedback.gitlab.com/forums/176466-general/suggestions/3962044-show-tags-in-commit-view
### Screenshots
![gitlab_feature_show_tags](https://gitlab.com/uploads/haynes/gitlab-ce/771c1a36bb/gitlab_feature_show_tags.png)

@dblessing Can you take a look at this MR as well please?

See merge request !297

Developer can push to protected branch if allowed

#1876

See merge request !1418