Code to define modeltype RM-2380

create a modeltype table used by models and pfts. The table is
initialized with the types already in the models (not pfts). All models
and pfts are associated with a modeltype next.
User can add/edit modeltypes and see the pfts/models associated with it.
Actually, the models index_table partial: app/views/models/_index_table.html.erb

I added a note there that the argument to "sortable" needs to be changed.