Bug fixes

This fixes two bugs, one was happening when deleting a record, json was getting returned causing problems for ember-data: http://discuss.emberjs.com/t/assertion-failure-when-deleting-record-with-hasmany-relationship/4537/2   - this fixed worked here too, removing the json returned from the adapter fixed the assertion failure.

The second bug was harder to track down, when loading data from indexeddb data was getting normalized twice, this would cause some transforms (like date) not to work the second time.  extractArray in the serializer was normalizing the payload after extractSingle had already normalized it.  This seems to work better.