python: add sphinx doc configuration
python/docs: add .. so sphinx configuration syspath
python: add generated pb2 module
python: mirror deps in requirements.txt
python: freeze requirements
python: clean dependencies
Merge https://github.com/GoogleCloudPlatform/google-cloud-datastore into merged-sphinx-docs
Merge pull request #22 from proppy/merged-sphinx-docs

Merge sphinx doc generation into master branch