Fix a bug where running all tests with sqlite (while postgres is     installed and available), would cause failures while creating the fixture models, as the TestingID model was pointing at a non-existant SQLite database.
Fix a bug where running all tests with sqlite (while postgres is
    installed and available), would cause failures while creating the
fixture models, as the TestingID model was pointing at a non-existant
SQLite database.

coleifer/peewee,coleifer/peewee,coleifer/peewee