Fix GitHub project's link in the import page when provider has a custom URL

Closes gitlab-org/gitlab-ee#478

See merge request !3803

use ! rather than # for merge request references

Fixes https://gitlab.com/gitlab-org/gitlab-ce/issues/15278

See merge request !3740

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

Add configurable shared runners text

cc @axil @rspeicher @grzesiek 

See merge request !3750

* '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