[api] support auto-accept for requests.

Urgently required for cleanups of build.opensuse.org
[backend] support "accept_at" element in backend request parser (even when not used anymore)
[api] fix validation of grouplist answer
[backend] backend does not know group definitions, blacklist it for backend parser test
[dist] install sphinx work dir
[dist] fix ownership of directories
[backend] disable sqlite databases for createrepo runs (0.9.9 and newer).
[api] Remove duplicates.
[dist] avoid broken yum-common packages
[webui] show accept_at informations in webui when showing a request
[webui] Make clear what the listed requests are about. Merge all into one table...
[api] test also that default reviewers got added when a non-maintainer is submitting a request
[webui][api] added edit/delete functionality with permission checks
[webui][api] edit and delete both route through different methods now.
[webui][api] refactored permission check. Added condition for required params. Handingly unknown request ids for comment
[webui][api] moved field checks to controller and some more refactoring.