added bio to speakers
Added timeslots and initialized them
Added timeslot editing (not yet complete)
Remove start_time end_time from speakers. Join with timeslots should be used instead
Added timeslot to the speakers form
Added selected value to the form
changes to time slot data type, small layout changes for  speakers form
Removed method for time_slot
Added language to speaker
Added language to speaker
Bug fix for migration
bug fixes in timeslot change data type migration
ChangeDataTypeForTimeSlot down function fix
Merge remote-tracking branch 'origin/master' into agenda
Updated with master.