GitLab

Created by: riyad

Refactors and documents the satellite code

• Move anything satellite related into the Gitlab::Satellite module
• Extract common code from actions (i.e. edit file, automerge) into the new Gitlab::Satellite::Action class
• Rename all actions *Action and make them inherit Action
• Move satellite cleaning code from actions into Satellite
• Move locking into Satellite
• Log all failed Git commands in actions
• Fix Git timeout being ignored
• Update method docs and clarify code