Ports changes to models and model tests along with some settings changes...

... from feature/tracks_activation
I don't really see the need for this class method.  For one thing, there are actually two exceptions that Django might throw when performing a `get` and this only deals with one.  It also looks like it's also only being used in one place below that I think has an opportunity to be modified anyway.  Rather than save a few lines and have a method on an abstract class, I'd prefer to see the try/except used where it's needed.