Improve performance of user profiles, finding groups, and finding projects

This MR improves the following:

* Rendering of profile pages and Atom feeds
* Finding groups (using GroupsFinder & friends)
* Finding projects (using ProjectsFinder & friends)

Initially this MR was intended to only improve rendering of Atom feeds, but over time other fixes were introduced as well as the same code was the cause of all these problems.

See merge request !1790

Add clipboard button to merge request cross-project reference

See merge request !1847

Award Emoji

This it first iteration of award emoji feature.
We have plan to extend emoji picker by the next release.

For now, you can add award by clicking to the emoji picker or posting a regular comment with emoji like "👍" and any other. You can post not only emoji that listed in the emoji picker.

See merge request !1825

Commits without .gitlab-ci.yml are marked as skipped

- Commits without .gitlab-ci.yml are marked as skipped
- Save detailed error when YAML syntax

This also fixes: #3521 #3546 

/cc @jacobvosmaer 


See merge request !1827

Add a fallback for Safari copy-to-clipboard

Also, hide the tooltip in a less stupid way.

Closes #3547

See merge request !1844

Improve personal snippet access workflow.

Replaces !1709

Fixes #3258

See merge request !1817

Add option to create merge request when editing/creating a file

Replaces !1611 

Fixes #3059

See merge request !1820

Fix 'Attach a file' link in new tag form

Also removed a little bit of code repetition :)

See merge request !1834

Update gitlab-shell documentation to 2.6.7



See merge request !1836

Add link to git-lfs client  [ci skip]



See merge request !1832

Check which folders and archives should be packed before passing to tar command.

If user uses backup task with SKIP and skips one of the archives listed(uploads, builds, artifacts) backup create will give an error: `Cannot stat: No such file or directory`.

This MR fixes that by checking for skipped items.
Additionally, compact everything to avoid `TypeError: no implicit conversion of nil into String` errors.

See merge request !1824

Documentation for Git LFS

Doc explaining how to use Git LFS, how to use Git LFS with GitLab, known issues and troubleshooting tips.

See merge request !1813

Deploy page should be shown for all pages not just root

Related to change already merged to Omnibus - gitlab-org/omnibus-gitlab!540

This change makes it so the deploy page is shown on all GitLab pages if the page exists. Users will no longer receive the 502 when deploys are happening.

See merge request !1828

Do not limit workhorse POST/PUT size in NGINX

Limiting, if any, should happen in gitlab-workhorse.

See merge request !1831

Backport relevant changes from gitlab-org/gitlab-ee!51

To do:

- [x] Update gitlab-shell

See merge request !1822

[ci skip]

Correctly set comparison first commit when range includes a merge commit

Fixes #3207.

See merge request !1814

See merge request !1705

Add notification to the former assignee upon unassignment

Replaces !1769

Fixes #3395

See merge request !1818

Prevent the last owner of a group from being able to delete themselves
by 'adding' themselves as a master

Replaces !1708.

Fixes #1111.

See merge request !1815

See merge request !1816

[ci skip]

[ci skip]

Don't render note edit forms for visitors

Reverted #9820, github/task_list need a form, textarea for update.

Revert "Merge pull request #9820 from huacnlee/avoid-render-form-in-notes-list"

This reverts commit 63144cd0, reversing
changes made to 8ab5df9d.

Reverts https://github.com/gitlabhq/gitlabhq/pull/9820

See merge request !1804

Fix md syntax in doc/api/commits.md

Ensure variable in mail is evalled

I received this snippet in the mail:

```
Content-Type: text/plain;
 charset=UTF-8
Content-Transfer-Encoding: 7bit

Project #{@old_path_with_namespace} was moved to another location

The project is now located under
```

This MR fixes it.

Notes:

* I did a quick grep on other 'text.erb' files, but this was the only one with this type of error
* I made no changes to the specs. The only [spec](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/spec/mailers/notify_spec.rb#L412) I could find passes because (I assume) the correct value is in the html-part

See merge request !1706

Make ProjectWiki touch Project#last_activity_at after wiki actions

Closes #3026

See merge request !1803

Rewrite HTTP links to force TLS, where possible

I got annoyed at the fact that the links on the profile page don't force the use of TLS, so I grepped through the entire source tree, tested all the links I found, and replaced them if possible.

See merge request !1806

Create milestones in the group

When you work with groups its quite often you want to create same milestone in multiple projects. This MR allows you to do so

For #3488 
Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

See merge request !1797

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

8.2.rc1 documentation updates

[ci skip]

See merge request !1798

Closes #3026

This reverts commit 63144cd0, reversing
changes made to 8ab5df9d.