Commented the code in ga_auth

Minor documentation update

Minor RST error

Implement oauth2 for accessing google analytics

- Provided a command (getauthtoken) to go through the auth flow and have
the user's oauth credentials written to local disk.
- Make sure loadanalytics command uses the token file to authenticate on
the request
- Added documentation on how to get the credentials (from google) to allow
for the oauth2 flow.
- Added google-api-client to the requirements

Initial iteration

Initial commit