Log to application.log when an admin starts and stops impersonating a user

Closes gitlab-org/gitlab-ee#536

See merge request !4028

Use new build badge URLs

Use new build badge URLs to follow the instruction at [the project badges](https://gitlab.com/gitlab-org/gitlab-ce/badges).

See merge request !4037

Merge request widget displays TeamCity build state and code coverage correctly again

## What does this MR do?
This MR contains a fix for a regression introduced in `8.7`. In former version, the TeamCity build status was always displayed correctly. In `8.7` the build state is still checked, but the UI is not updated correctly any longer.

## Are there points in the code the reviewer needs to double check?
The changes are quite simple, so please simply double check them.

## Why was this MR needed?
This MR is needed to make the TeamCity build status working again.

## What are the relevant issue numbers?
#17080 

See merge request !3998

Use `number_to_human_size` helper to show repository size

This will intelligently format large repository sizes in GBs (or,
shudder, TBs).

Also, removes `rescue` clause from `repository_size` helper.
The repository size has since become calculated (and cached)
more intelligently, and this should no longer be necessary.

See merge request !4047

The repository size has since become calculated (and cached) more
intelligently, and this should no longer be necessary.

This will intelligently format large repository sizes in GBs (or,
shudder, TBs).

Sanitize repo paths in new project error message

Closes #17243

See merge request !4029

Closes #17243

Remove break-all from links

Closes #17000

See merge request !4042

Fix file list page border colors



See merge request !4008

Improve milestone page UI

* remove button after edit button
* use hex value for text color
* re-use existing text color variables
Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

See merge request !4014

Expire repository exists? and has_visible_content? caches after a push if necessary

See merge request !3975

Closes #17012

Remove unused .contributed-projects class

While working on #13401 and trying to add a new tab to the user profile
page, I came across this. I noticed that the `contributed-projects`
class was only being used in order to select the div in the tests. For
consistency with the other tabs, I decided to remove this class and use
the div's id for the selector.

See merge request !3945

Limit the number of merge requests per project to avoid long seeds in development environment

This step was taking a long time because seed_fu creates N / 2 merge requests for each repo, where N is the number of branches for that repo. At the time of this writing, there are 234 branches on the gitlab-ce repo, leading to 117 merge requests.

See merge request !4032

Use the new admin settings for gravatar

Fixes gitlab-org/gitlab-ce#14826

See merge request !3988

Make files list more compact by reducing row height from 47px to 44px
Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

cc @jschatz1 @skyruler 

See merge request !4007

Documentation fix in CI SSH keys setup

In recent versions of Docker, the `/.dockerinit` file doesn't exist any more when running inside a container. That file is used in the example here to detect whether the runner is running inside Docker or not. Change it to check for the existence of `/.dockerenv`, which does exist in all current versions of Docker.

See merge request !3938

Use 'exec' in Unicorn and Sidekiq launch scripts

When running Unicorn or Sidekiq in the foreground this change removes
an intermediate /bin/sh process. This makes process supervision in the
GitLab Development Kit more reliable.

This change does not affect Omnibus-GitLab (because there we do not
use these launch scripts). Installations from source do use the launch
scripts but for the standard GitLab init script this change will not
make a difference.

Custom installations using Upstart or Systemd may be affected however,
because under certain configurations these systems count exactly how
many forks happen during process startup, and we are reducing that
number by one here.

Closes https://gitlab.com/gitlab-org/gitlab-development-kit/issues/116

See merge request !3964

This step was taking a long time because seed_fu creates N / 2 merge requests
for each repo, where N is the number of branches for that repo. At the time of
this writing, there are 234 branches on the gitlab-ce repo, leading to 117
merge requests.

Closes gitlab-org/gitlab-ee#536

Use Rugged's TagCollection#create instead of gitlab-shell's Repository#add_tag for better performance

This was originally opened at !1757 by @pcarranza but I changed it to use Rugged instead of gitlab_git, following @DouweM's request.

Once this is merged, https://gitlab.com/gitlab-org/gitlab-shell/merge_requests/26 will be mergeable too.

See merge request !3745

Fix typo in user steps feature file

Just came across a typo in the user steps file.

See merge request !3943

Update patch_versions.md with explicit --with statement for db gem group

## What does this MR do?
Updates `patch_versions.md`'s instructions on installing gems to explicitly install either the postgres or mysql groups.

## Are there points in the code the reviewer needs to double check?
No, but thank you for your time.

## Why was this MR needed?
I performed the steps listed in `patch_versions.md` and ran the command for updating postgres gems. Bundler told me at the end that it had not installed the postgres gem group, which caused the next step, migrating the DB, to fail for obvious reasons.

Changing the command to `--with postgres` made it install the postgres gem group, and db:migrate then passed.

## What are the relevant issue numbers?
None

## Screenshots (if relevant)
N/A

See merge request !3955

# Conflicts:
#	Gemfile.lock

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

Use Rugged's TagCollection#create instead of gitlab-shell's Repository#add_tag for better performance
Signed-off-by: Rémy Coutable <remy@rymai.me>

feature proposal issue template in contributing guide

This adds a feature proposal template to the contribution guidelines for internal and external use.

Fixes #15448 

cc @markpundsack @stanhu @dzaporozhets 

See merge request !3967

Enable LstripRstrip cop

This requires no code changes since it doesn't actually change anything in the codebase, just preventative.

See merge request !3959

Instrument methods used in email diffs

See merge request !4038

Remove unnecessary method call in events view

Since `User#to_param` already returns `User#username`, we don't need to
pass in the user's username. Changing this also helps us obey LoD.

See merge request !3996

Initialize wikis on legacy projects during check

Closes https://gitlab.com/gitlab-org/gitlab-ce/issues/4173

Helps https://gitlab.com/gitlab-org/gitlab-ce/issues/15423

See merge request !3931

Revert "Remove the Devise Async gem."

This reverts commit 1cc614f2.

It was causing the ActiveJob integration to fail, so unfortunately we'll have to add the gem again.

Resolves #17250.

See merge request !4027

Improve uniqueness of field names on the signup form

Closes https://gitlab.com/gitlab-org/gitlab-ce/issues/15075

See merge request !3826

Make all of the nested constant instrumentation for core app code work
the same way, add mailer instrumentation, and add instrumentation to the
premailer gem.