Refactor to handle new backend profiles.

Let `ngHalMock.stubEnclosure()` receive optional mixin uris before the enclosure url.

Automatically digest as often as possible for ngHalMock promises.

Fix issue where transformations happen more than once on ngHalMocked objects.

Refactor stories module for better readability.
add toResolveTo matchers for clearer tests
Merge pull request #14 from chrisrhoden/chore/backend_profile_upgrades

Refactor to handle new backend profiles.