Ensure all promises are waited on in tests
Ensure all promises are waited on in tests

The indexed-db service will now register a test waiter, which checks if there is an open item left in the promise queue.
Additionally, this commit refactors how the promise queue is kept, and ensures that there are also entries there for find/query/findAll/queryRecord.

mydea/ember-indexeddb,mydea/ember-indexeddb