Remaining Issues from ember-data 13 upgrade

With the old ticket closed due to merge, we need a place to discuss the remaining issues with the upgrade.

As I understand it the only show-stopping issue is the lack of error handling.
The other issue is with the tests, as it is apparent they don't accurately reflect all of the code used by the adapter.

Have you done any investigating into why error handling has stopped working yet?

With the testing, perhaps we could use [ember-dev](https://github.com/emberjs/ember-dev).
They seem to have a very nice framework for testing, which is used by ember-data as well as the main ember.js repo.

I believe the only things involved up front for this change is requiring it in the gemfile, moving the tests into the package subdirectory, and shifting a few things around in the rakefile.  This transition would also remove the need for the symlinks into the test folder (which do not work on windows).

- [x] Error Handling
- [x] Use ember-dev for test framework
- [x] Less Intrusive Tests