Fix typo in README.md
Three fixes to make the tests work again with latest ember

1. Recursive promises are always assimilated into one another, so that
errors are properly passed along.

2. Dropped the array clean-up in loadRelationshipsForMany, which
produced a spurious undefined element.

3. Make findMany honor the opts.allowRecursive flag.
Fix findQuery

findQuery previously included all the records, which fulfilled the last
of the tests in query.
findMany rejects upon missing elements
Use Ember.copy in find