* Removed support for AdWords v201607.
* Improved logging support. Can now specify logging configuration from the
configuration file.
* Added new GoogleAccessTokenClient, a non-refreshable client that only requires
the access token.
* Resolved issues:
- Issue 84: https://github.com/googleads/googleads-python-lib/issues/84
- Issue 171: https://github.com/googleads/googleads-python-lib/issues/171