Altered how Resources/Collections can be constructed to allow for more dynamic selection of base class.
Updated the ``Session`` & its cache to allow caching multiple types of a given class (based on its base class).
Forgot the ``__init__.py`` like a newbie.
Back to a passing suite after today's fallout.
Merge branch 'customizable-resources' into develop
More progress on the S3 resource integration tests.

Next up, relations.