Event migration

Jon and Amal collaborated on this.
replaced the event model fields (event_date, start_time, end_time) 
with (start_datetime, duration).  
This removes the need for the from_must_come_before_to validation.
Many changes to accomodate tests, event _form view, events controller services (create and update), and more.
No migration test. I don't know if it's necessary, but if you insist, then I'll work on it.
No, I don't think so. First, the data:format that I removed didn't have any noticeable effect. Second, the default/input value for the field needs to be specified in the same format that the datepicker or timepicker is looking for.  For the datepicker, it was already just fine even without the "format_datepicker" function, i.e. the datetime date is in a good format for datepicker, and the datepicker control ignores the time that follows the date.  But it just seems like it's cleaner and more descriptive to include the 'format_datepicker' function call.  For the timepicker, it expects data in the form: hour:minute am/pm.  There probably is a way to modify the timepicker to use a different format (e.g. 24 hour), but this interface is very nice. i hope that answers your question... I might not understand your question.