Fix client_max_body_size for workhorse

Bringing this back because it appears that `error_page 418` hack that we use to reuse the gitlab-workhorse block is not using the `client_max_body_size` within that block.

See merge request !550

Omnibus version v5.0.0

Fixes #834

See merge request !548

Fix a bug where issue closing pattern is not passed to config.

Fixes #919 

See merge request !549

Create /var/log/gitlab explicitly to apply correct permissions.

Fixes #723

See merge request !546

Add sidekiq concurrency setting.

Fixes #671 

Fixes #922

See merge request !547

Add replication pg_hba.conf entry

PostgreSQL needs a specific replication entry in pg_hba.conf for wal replication to work.

See merge request !545

Expose artifacts options in omnibus package

Related to: https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/1869

It also creates directory for `/artifacts` and `/lfs-objects`.


See merge request !544

- Create directories for artifacts/ and lfs-objects/

Limit put/post under workhorse.

Due to gitlab-org/gitlab-ce!1831

See merge request !543

Skip artifacts and lfs objects in preinstall backup.



See merge request !542

Fix docker image pushing

- to :latest only stable releases are pushed
- to :rc rc and stable releases are pushed

@marin this should get picked to stable

Fix for #948 


See merge request !541

- to :latest only stable releases are pushed
- to :rc rc and stable releases are pushed

Make deploy page show on all pages, when up

This change will make Nginx display the deploy page for *all* GitLab pages when it's up. Previously only the root/index of GitLab would show deploy. Everyone else may get errors if visiting a page directly. 

See merge request !540

Huge clean up GitLab CI references

No header title was removed, those that refered to CI got the following text in them:

> This section is deprecated for GitLab 8.0 and later versions.

Those below are the ones I haven't touched:

```
ack gitlab-ci doc/


common_installation_problems/README.md
275:### Error executing action create on resource cron[gitlab-ci schedule builds]
278:1. Check if user `gitlab-ci` is in `/etc/cron.deny` and if yes remove it. You can add the `gitlab-ci` user to `/etc/cron.allow``.
279:1. Check if you have PAM enabled and if gitlab-ci user is allowed to access crontab. If yes, try changing your `/etc/security/access.conf` to allow the user access to the resource, for example `+:gitlab-ci:ALL`.

README.md
45:- [Updating from GitLab CI version prior to 5.4.0 to the latest version](update/README.md#updating-from-gitlab-ci-version-prior-to-540-to-the-latest-version)
52:- [GitLab CI shows GitLab login page](common_installation_problems/README.md#gitlab-ci-shows-gitlab-login-page).

update.md
46:See [doc/update/README.md.](doc/update/README.md#updating-from-gitlab-ci-version-prior-to-540-to-the-latest-version)

gitlab-ci/README.md
3:You can run a [GitLab CI](https://about.gitlab.com/gitlab-ci/) Coordinator
```

Closes #913 

See merge request !534

Mattermost 1.2.1

Part of #942 

See merge request !537

Version 0.4.2 of workhorse.



See merge request !538