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.
I prefer no tabs in indentation.  This file has lots.  I tell the students to use "git diff --check master" to see all the whitespace they've introduced on their branch (see the https://github.com/PecanProject/bety/wiki/Code-Formatting-Guidelines%3A-Whitespace-Conventions Wiki page).  You don't _have_ to fix this, but if you don't I might.