WIP: Added Front end Functionality to allow three part editing

@stephensanchez , I am doing the same.  Here is my rough draft for the front end.  Haven't yet worked on styles or tests.
Further down, `validate_dates` calls `resolve_dates`, which operates on an arbitrary list of start/end datetimes.  It's fine to change the method signature for `validate_dates`, but then `validate_dates` will need to do that translation.