Create/edit flavors directly in the resource class form.

The formset in the resource class create/edit form now starts empty,
and allows the user to create or edit the flavors of that class
directly. Flavor templates are no longer used.

The formset starts with a single empty row at the end, for adding a new
flavor, and a "Delete" column with checkboxes for deleting existing
flavors.

If javascript is available, there is a link for adding more empty rows
and the empty line from the end is removed, and the checkboxes are
replaced with a cross icon, for deleting the rows instantly.

All traces of flavor templates have been removed from tuskar-ui.

The Max VMs field has been temporarily removed -- it will be added in
further iterations.

Change-Id: I1ff4c9f90657c62e7c5f45a4b7874524b9df204c
Implements: blueprint remove-flavor-templates