Merge branch 'zj-mattermost-slash-config' of gitlab.com:gitlab-org/gitlab-ce into zj-mattermost-slash-config

Merge branch 'zj-mattermost-slash-config' of gitlab.com:gitlab-org/gitlab-ce into zj-mattermost-slash-config

[ci skip]

Merge branch 'zj-mattermost-slash-config' of gitlab.com:gitlab-org/gitlab-ce into zj-mattermost-slash-config

Merge branch 'zj-mattermost-slash-config' of gitlab.com:gitlab-org/gitlab-ce into zj-mattermost-slash-config

Fix sizing of avatar circles; add border

* Adds border to group and project avatars
* Fixes cut-off circles
![Screen_Shot_2016-12-20_at_8.25.12_AM](/uploads/24e0eedf001f230300a316c504af59d4/Screen_Shot_2016-12-20_at_8.25.12_AM.png)
![Screen_Shot_2016-12-20_at_8.24.59_AM](/uploads/23450bf1f99b8075a043dd5512185e91/Screen_Shot_2016-12-20_at_8.24.59_AM.png)
Closes #25733

See merge request !8194

Allow unauthenticated access to Repositories Files API GET endpoints

See merge request !8149

Use gitlab-workhorse 1.2.1

More prometheus metrics, other small fixes.

See merge request !8197

hides new issue btn for not loggedin user

## What does this MR do?
This MR closes #25093 #25180
## Are there points in the code the reviewer needs to double check?
NR
## Why was this MR needed?
Prevent issue creation for no logged in user and some confusion related to 
## Screenshots (if relevant)

## Does this MR meet the acceptance criteria?

- [x] [Changelog entry](https://docs.gitlab.com/ce/development/changelog.html) added
- Tests
  - [ ] All builds are passing
- [x] Branch has no merge conflicts with `master` (if it does - rebase it please)
- [ ] [Squashed related commits together](https://git-scm.com/book/en/Git-Tools-Rewriting-History#Squashing-Commits)

## What are the relevant issue numbers?
Closes #25093, #25180

See merge request !8175

Make 'unmarked as Work In Progress' system note more consistent

See merge request !8193

Memoize Milestoneish#issues_visible_to_user to reduce lookups

https://gitlab.com/gitlab-org/gitlab-ce/issues/25748

See merge request !8146

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

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

Allow Repositories API GET endpoints to be requested anonymously

Closes #4269

See merge request !8148

Smarter refreshing of authorized projects

This MR reworks the way `User#refresh_authorized_projects`, resulting in a much more efficient process leading to fewer dead tuples.

Related issue: https://gitlab.com/gitlab-org/gitlab-ce/issues/25257

See merge request !7956

Remove unnecessary method `build_user` from model `User` 

Closes #25678

See merge request !8162

Fix member with expiration date feature spec

See merge request !8186

Memoize Milestoneish#issues_visible_to_user and counts to reduce lookups
Milstoneish SQL optimised with project, but still slow on GlobalMilestone

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

Move admin projects spinach tests to RSpec

Part of https://gitlab.com/gitlab-org/gitlab-ce/issues/23036

See merge request !8174

Add doc for pipeline duration

The description was copied and modified from !6084

See merge request !6445

Add doc for the Gitea importer

This adds documentation for !8116. It's mostly a copy/paste of the GitHub import documentation without the OAuth parts since Gitea is not yet an OAuth provider.

Part of #22348.

See merge request !8139

It adds a brand new importer for Gitea!

This is a continuation of !6945 started by @bkc.

Gitea aims to be 100% GitHub-compatible but there's a few differences:

- Gitea is not an OAuth provider (yet): https://github.com/go-gitea/gitea/issues/27
  - This means we cannot map Gitea users given an assignee ID => assignees are not set on imported issues and merge requests
- No releases API for now: https://github.com/go-gitea/gitea/issues/330
- API version is `v1` (GitHub is `v3`)
- The IID field for milestones is `id` compared to `number` in GitHub.
- Issues, PRs, milestones, labels don't have a `url` field (the importer now fallback to `''` in that case)

**Known issues:**

- Comments are not imported because comments JSON always have a blank `html_url`/`issue_url`/`pull_request_url`, so the IID cannot be extracted and the issuable cannot be found... :( This is tracked in https://github.com/go-gitea/gitea/issues/401, and solved by https://github.com/gogits/gogs/pull/3624 but this needs to be submitted / merged in Gitea.

This is noted in the documentation.

## Are there points in the code the reviewer needs to double check?

1. I've made `Import::GiteaController` inherit from `Import::GithubController` since both controllers should be identical in the long-term and their current differences are small.
1. I've added a base `IssuableFormatter` class from which `IssueFormatter` & `PullRequestFormatter` inherit
1. I've added shared examples for GitHub/Gitea importer classes
1. I've made `Gitlab::ImportSources` more robust and tested! 🎄 
1. I've added routing specs for import routes! 🎄 

Closes #22348

See merge request !8116