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.
"modeltypes.name" not "modeltype.name".  I think the general rule is that that the table name in the first argument of the `sortable` method has to match the SQL table name (though there may be some exceptions).