For the schedule versioning in the admin interface (having multiple possible shcedules) we need to change some models and associations. It has also been create a rake:move_events_attributes task to migrate the data.
User Interface addapted to make use of the introduced associations and models
* Consistent route/model/controller/view layout
* Get rid of unused photos, speakers, dietchoices, social_events controllers
* Drop unused :public from Rooms and :description from CallForPapers