Add filter by metadata to ServersController#fetch_recordings

Filter by metadata in getRecordings is available on Mconf-Live, see
https://github.com/mconf/bigbluebutton/commit/f8180d3cee643c24fdc4b205aeee11d9c5afdac5
Add RoomsController#fetch_recordings

To fetch the recordings for a single room.
Updated bigbluebutton-api-ruby to 1.2.0, which includes the possibility
to pass metadata fitlers to getRecordings.
Add RoomsController#recordings