coplanar/modeleditor: Fix the Create/Save button live binding

The live binding to switch between the 'Create' and 'Save' button
wasn't working properly. This seems to be because jquery-ui reparent
the content of the button. To workaround this problem use 2 buttons
and toggle their 'display' css property using a live binding.
GV: Hide the status field when creating an Event or Hostel Booking
coplanar/control/objectview: Remove a useless assignment