Use abstract base class for oauth driver

Use the abc module for managing abstract base classes in the driver
layer.

bp abstract-base-class-drivers

Change-Id: I8c9b095ee012a4faca90ed026cea846b7d178dc2
Use abstract base class for endpoint_filter driver

Use the abc module for managing abstract base classes in the driver
layer.

bp abstract-base-class-drivers

Change-Id: I0222f062adde75cdb53015f6b908a15f9f438b98
Merge "Use abstract base class for oauth driver"
Merge "Use abstract base class for endpoint_filter driver"