* Added support for v201811.
* Removed support for v201711.
* Removed examples for v201802.
* Remove ContentMetadataKeyHierarchyService
* Added version parameter to PQL utilities to account for statement
differences among API versions. This parameter defaults to the most recent
API version. If you update your Python client library but don't plan on
migrating to the newest API version, you might need to explicitly declare the
version for the PQL utility to use.