Allow LDAP to handle external users, based on users' group memberships

Fixes gitlab-org/gitlab-ce#4009

These MR adds functionality to the `LdapGroupSync` feature that allows
it to receive an array of group names, in order for the members of these
groups to be marked as external users.

See merge request !432

Remove colorize methods that weren't in CE.

This is a follow-up from gitlab-org/gitlab-ce!4425, which replaced colorize methods equivalent Rainbow methods e.g. `.red` with `.color(:red)`.

The gem was replaced due to licensing conflicts. This fixes up the last few uses the gem had in EE.

See merge request !438

attr_encrypted 3.0.0

Adds algorithm to the pages domain key and remote mirror credentials encrypted attributes for forward compatibility with attr_encrypted 3.0.0.

aes-256-cbc is the default algorithm for attr_encrypted 1.x, but the default is changed in 3.0 and thus must be declared explicitly.

See https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/4216/ for more information. This will prevent OpenSSL errors once the code from that MR is merged into EE.

See merge request !435

Adds algorithm to the pages domain key and remote mirror credentials encrypted attributes for forward compatibility with attr_encrypted 3.0.0.

aes-256-cbc is the default algorithm for attr_encrypted 1.x, but the default is changed in 3.0 and thus must be declared explicitly.

See https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/4216/ for more information. This will prevent OpenSSL errors once the code from that MR is merged into EE.

CE upstream



See merge request !437

CE upstream

Could you guys please resolve next conflicts (the conflicts just committed to the branch):

@dzaporozhets - `app/views/layouts/nav/_project_settings.html.haml`

@iamphill `app/views/projects/_builds_settings.html.haml` and `app/views/projects/edit.html.haml`

@annabeldunstone `app/views/projects/_home_panel.html.haml`

@jschatz1 - `app/views/shared/issuable/_form.html.haml`

- [x] `app/views/layouts/nav/_project_settings.html.haml`
- [x] `app/views/projects/_builds_settings.html.haml` 
- [x] `app/views/projects/edit.html.haml`
- [x] `app/views/projects/_home_panel.html.haml`
- [x] `app/views/shared/issuable/_form.html.haml`
- [x]  `app/views/layouts/nav/_project.html.haml`
- [x]	`app/views/projects/hooks/index.html.haml`

See merge request !425

These specs do not exist in CE and don't add anything useful themselves.
There's no application code that initializes a JiraIssue instance and it
currently behaves exactly the same as a regular ExternalIssue.

Document the API endpoint for gathering a build log

## What does this MR do?

Adds documentation for gathering a trace build log via the API. Documenting the following:
https://gitlab.com/gitlab-org/gitlab-ce/blob/de20bd5b31715f096db3fb0155c82b0eea992b6c/lib/api/builds.rb#L98-110

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

Please verify that a curl request using the same format as documented works

## Why was this MR needed?

No documentation currently exists

## What are the relevant issue numbers?

#18015 

## Screenshots (if relevant)

See merge request !4467

Fix link to current design reference in the CONTRIBUTING guide

## What does this MR do?

It fixes an outdated link by replacing it with the up-to-date one.

See merge request !4439

Allow bulk-assign labels to issues

- [x] Allow bulk-assignment labels.
- [x] Show indeterminate state for labels present on selection.
- [x] Remove existing labels from selected items if label gets unmarked.
- [x] Fix conflicting tests.
- [x] Write tests.

Closes #13499 and #15489

See merge request !3917

Instead of passing `remove_label_ids`, just pass an empty array for
`label_ids` (and don't pass `add_label_ids` or `remove_label_ids`).