* Move gitaly, git-lfs and 2FA logic out from gitlab_shell.rb
* Streamline parsing of origin_cmd in GitlabShell
* Utilise proper HTTP status codes sent from the API
* Also support 200 OK with status of true/false (ideally get rid of this)
* Use HTTP status constants
* Use attr_reader definitions (var over @var)
* Rspec deprecation fixes