[auth] pass `repo` instead of `vreg` to SessionManager and AuthenticationManager Those object actually need a repo object to connect and create new session object. They used to retrieve the repo object using ``vreg.config.repository()``. I'm trying to sanitise the initialisation stack and get ride of ``config.repository()``, a function that mix factory and cache. Retrieving the vreg from the repo is trivial (``repo.vreg``) so we now pass the repo object instead of the vreg.

option_group_changed('port', 'main', 'web')
option_group_changed('query-log-file', 'main', 'web')
option_group_changed('profile', 'main', 'web')
option_group_changed('max-post-length', 'main', 'web')