run custom model tests when checking model

[pkienzle]

The code in sasgui/perspectives/calculator/pyconsole.py loads and runs the model when editing is complete but it does not run the tests that are recorded in the model. Rearrange the code in sasmodels/model_test.py so that it can be called from sasview on custom models. This could be done either within the unittest framework, or by moving the test cases out of the unittest framework so that they can be called from unittest, from the gui and from the sasmodels command line.

Verbose output showing q → I(q) for each test would be best.