Support Backbone 1.1.0 and add `wipe` methods.

This moves Backbone.ModelFactory forward to support the newest
version of Backbone and removes support for versions pre-0.9.9.

Some clarity is provided around using the `Model` property of
factory-generated constructors. Basically, you shouldn't have
to anymore - the factory-generated constructors should support
everything that's needed.

Additionally, adds the `wipe` method to constructors and model
instances.