Documenting the fact the more_results is unfit for use in datastore.
Merge pull request #287 from dhermes/document-more-results-failure

Documenting the fact the more_results is unfit for use in datastore.
Moving encrypted key to regression subdirectory.
Merge pull request #286 from dhermes/move-encrypted-key

Moving encrypted key to regression subdirectory.
Implements group_by, projection and offset on datastore Query.

In addition, __eq__ was implemented on datastore.key.Key
to allow for easy comparison.
Addressing corner cases for datastore.Key.__eq__.

These corners are a direct result of #274.