WIP: Entries by type

Add the ability for the container to list all entries of a specific type.  This is part of an effort to fix the Ember Inspector's Data tab compatibility with module based resolvers (such as EAK).

99% of the work was done by @yapplabs @lukemelia @stefanpenner @brendanoh over the course of 2 months.

I'm just going to complete the remaining todos and make sure it's ready to be merged and works well with Ember Inspector.  I hope to finish it this weekend.

- [x] Make sure tests passing in Ember and minor fixes.
- [x] Fix issues with `container-debug-adapter` registration / injection.
- [x] Update ContainerDebugAdapter#catalogEntriesByType to return an array of strings (model names) instead of classes.
- [x] Make sure the Inspector supports both string and classes.
- [x] Rely on the model's key instead of `toString` .
- [x] Implement the `container-debug-adapter` in EAK's resolver (https://github.com/stefanpenner/ember-jj-abrams-resolver/pull/31)
- [x] Clean commits