[webui][api] More Gemfile Documentation
[webui] Introduce pundit as authorization system
[api] Fix for a bug in markdown preprocessing
[backend] optional flag element to add disabled repositories
[api] commit indexed data in own transaction, to avoid to be rollbacked

otherwise it depends on the point of time when the backend gets started
[api] ensure that indexed data from start_test_backend get part of the database

It was just luck when the data got indexed and when it happened during a test case
the transaction rolled it back