Automations in GitLab (issues and MRs)

Depending on your project, you want to be able to:

• automatically add or remove labels on certain events
• automatically assign people (see also https://gitlab.com/gitlab-org/gitlab-ce/issues/3126)
• automatically open / close issues
• automatically link other issues, documents, etc

There are several ways we could achieve this in GitLab. Build them one by one, support Bots (better), and more.

This issue is to discuss the possibilities and path going forward. In response to https://gitlab.com/gitlab-org/gitlab-ce/issues/8938

cc @sytses @dzaporozhets