Verify found object is actually a commit in Commit.find

Execute hooks and services when branch or tag is created or deleted through web interface.

Fixes #2095.

Split up into commits to make it easier to see why what was changed :)

See merge request !1692

Use custom LDAP label in LDAP signin form.

Addresses https://dev.gitlab.org/gitlab/gitlab-ee/issues/238

![Screen_Shot_2015-03-13_at_15.43.19](https://dev.gitlab.org/gitlab/gitlabhq/uploads/e9f0d1ed7238701ecdbaa54d4f538d89/Screen_Shot_2015-03-13_at_15.43.19.png)

See merge request !1693

Fix import pages not working after first load.

Fixes #2102.

`OAuth2::Client` was deleting keys from the options hash in place, which made it incomplete the next time the import page was loaded. We dup it so this no longer happens.

See merge request !1691

Update Webhook documentation for tag and tag push events

Just a quick update to include the `object_kind` field in the Webhooks documentation.

See merge request !389

Enhance Markdown linebreak docs

The "Line Breaks" section within the Markdown docs was missing an example of creating a line break within a paragraph by ending a line with two spaces.

See merge request !335

Make Irker service check supported_events

63178a95 added the supported_events check for services. Since f84b7eef was just added, we should adjust it accordingly.

See merge request !367

Implement merge requests search

It is same search like we have at issues page. It allows to quickly
filter merge requests based on title or desription. I copy-pasted some
js code from Issues.js. In future search (filtering) logic should be
refactoed into one class for merge requests and issues

See merge request !1690

Conflicts:
	app/controllers/projects/merge_requests_controller.rb

Use same constant for amount of items per page

See merge request !1689

It is same search like we have at issues page. It allows to quickly
filter merge requests based on title or desription. I copy-pasted some
js code from Issues.js. In future search (filtering) logic should be
refactoed into one class for merge requests and issues

Prevent database query each time we render group avatar

Fixes #2118

See merge request !1688

Show asterisks instead of password in service edit form.

See merge request !1686

Block user if he/she was blocked in Active Directory

For gitlab/gitlab-ee#248

See merge request !1687

Style improvements to import page

See merge request !1685

Fix email images

## Dependencies:
This MR Depends on gitlab-org/html-pipeline-gitlab!4 being **merged and published** to rubygems.org

## What does this MR do?
This MR fixes the broken images in emails that occured scince we introduced access control for all attachments in 7.8.
The access control lead to broken images, because the user usually isn't logged into gitlab when opening the email in his mail client.
The solution to fix this, is to replace all images that were uploaded to gitlab as attachemnts with inline images in emails.

I only added one test for images in notes, because all notes share the same view. If it works fine for a note on a commit, then it'll also work the same for notes on a MR or on issues.

@DouweM can you review this please?

Closes #1161

See merge request !373

Fix missing GitHub organisation repositories on import page.

Private repositories belonging to organizations rather than users can't be imported because `client.repos(org.login)` was requesting `/users/:org_login/repos` (which only returns public org repo's), while we need `/orgs/:org_login/repos` (which includes both public and private). The `client.org_repos` method does this.

cc @marin This is a bug in 7.8.x, but I'm not sure if it needs a minor release now or if it can go in 7.9.

See merge request !1683

Add blue theme to GitLab

See merge request !1682

Emoji cheatsheet fix

Worked through the help text for emoji to properly reference and use EmojiOne tags. Removed the ninja and reworked the first sentence a bit, as ninja isn't supported by EmojiOne. Should resolve ticket #953.

See merge request !384

Conflicts:
	app/assets/stylesheets/generic/nav_sidebar.scss

Group controllers refactoring

Usefulness of this refactoring is not so obvious on CE codebase. But It will allow us to remove huge amount of code on the EE side.

See merge request !1684