Add another TimeField format

The format used by floppyfields to populate the field with model data is
%H:%M:%S. This prevents an exception if you save the form without
modifying any time fields.
Move event form to a partial

The add event form was moved to a partial so it could be reused for
editing events.
Implement edit_event endpoint

Updated the route and view to behavior similar to the add event
endpoint.
Rename add_form.js to event_form.js

This entry script is used on both the add and edit event page.
Add UI test for edit event form

This tests to make sure that datetime fields are converted from UTC to
localtime when populating the form. This is important so that when you
save the form without any modifications, your datetime values don't
increase by the local timezone offset.
Merge pull request #146 from kdeloach/topic/event-detail-edit-view

Edit event form