Use Twisted which function instead of relying on OS in test runner. Fixes #62.

Reviewed in https://codereview.appspot.com/8893044/
Add links about support and filing bugs to README. Fixes #72.

Reviewed in https://codereview.appspot.com/9596043/
Merge branch 'master' of github.com:GoogleCloudPlatform/endpoints-proto-datastore
Revert of Add _method_decorator argument to EndpointsModel.method and EndpointsModel.query_method.
Add offset alias property to be used in query_method.

* endpoints_proto_datastore/ndb/model.py
  (_EndpointsQueryInfo.__init__): Add _offset member.
  (_EndpointsQueryInfo._GetOffset, _SetOffset, offset): Add offset property.
  (EndpointsModel.OffsetSet, offset): Add offset property.
  (EndpointsModel.query_method.QueryFromRequestMethod): Add offset to
     query_options which is passed to fetch_page.