Library release 5.1.0

Release v5.0.4

Release 5.0.3

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