Release version 5.0.2

Releasing version 5.0.1

Release Google Ads API v3_0

Fix for types.py to include classes of dependent modules

Performance improvements, bump of Python version to 3.7

Changes for release v2_2 with performance improvements (googleads#194)

Removal of Python 2 support

Changes for release v2_2. (googleads#177)

* Google ads v2_1 release

* Fix formatting typo in README
* Add AdWords -> Google Ads migration examples

Update signature for customer_service.create_customer_client method t…

…o give

default values to optional parameters.