Googleads

* Added support and examples for DFP v201708.
* Removed support and examples for DFP v201608.

* Added support for AdWords v201708.

* 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

* Added support for AdWords v201705.

* Added more expressive python utility to build DFP PQL statements.
* Support building DFP SOAP entities with native python date/datetime objects.
* Added support and examples for DFP v201705.
* Removed support and examples for DFP v201605.

* Resolved issues:
- Issue 200: https://github.com/googleads/googleads-python-lib/issues/200
- Issue 196: https://github.com/googleads/googleads-python-lib/issues/196