add slack notifications for wiki pages
## What does this MR do?
Lets the Slack service be configured to send notifications when wiki pages are created or edited.
## Are there points in the code the reviewer needs to double check?
I'm just starting to get familiar with the Gitlab codebase and I was unsure on how to get the wiki page url to pass it to the slack message, on whether or not I needed to refactor the create/update methods for wiki pages from the controller to a service (but seemed necessary to test it better), and if I needed to add a column to the web hooks table or if the services table would have been enough. Please let me know if I should change anything and I will improve the MR, thanks for checking :)
## Why was this MR needed?
Related to #563 and fixes#4233.
See merge request !2998
Add raw build trace output
Closes#15308, #15147
Changes in the UI:
- on finished build:

- on running build:

See merge request !3767
Sanitize branch names for confidential issues
- When creating new branches for confidential issues, prefer a branch name like `issue-15` to `some-sensitive-issue-title-15`.
- The behaviour for non-confidential issues stays the same.
Closes#14566
See merge request !3671
Remove persistent XSS vulnerability in `commit_person_link` helper
Because we were incorrectly supplying the tooltip title as
`data-original-title` (which Bootstrap's Tooltip JS automatically
applies based on the `title` attribute; we should never be setting it
directly), the value was being passed through as-is.
Instead, we should be supplying the normal `title` attribute and letting
Rails escape the value, which also negates the need for us to call
`sanitize` on it.
Closes https://gitlab.com/gitlab-org/gitlab-ce/issues/15126
See merge request !1948
API: Present an array of Gitlab::Git::Tag instead of array of rugged tags
The annotated message was always `null` because the wrong array was presented.
The entity requires an array of `Gitlab::Git::Tags` instead an array of raw rugged tags was presented. Since a rugged tag does not respond to `message` to get the annotated message, this was always `null`.
See merge request !3764
* 'master' of dev.gitlab.org:gitlab/gitlabhq:
Add Changelog entry for group link permissions fix
Use guard clause to check ability to share project
Refactor method that shares project with a group
Check permissions when sharing project with group
Implement after_script which allows to do cleanups as part of the build process
This implements `after_script` in global context.
The `after_script` will be executed always after the job, even if the job were canceled.
This requires changes on Runner side that will be implemented in 1.2.
cc @tmaczukin @grzesiek
See merge request !3771
Added System Hooks for push and tag_push
Implements `push` and `tag_push` events for System Hooks.
They are based on Webhooks Events but without any deprecated item. We don't send commits too.
We are implementing this, to be used by Geo repository syncing (gitlab-org/gitlab-ee#76).
These hook events will be sent only when the respective configuration flags are set to true.
UI changes to admin screen will be made in another MR.
See merge request !3744