Define context.roles with base class
Define context.roles with base class

In Ia575ba803a0fb70f39146bd75d381ed19414bd23, oslo.context (2.2.0)
added roles support in the context itself. This passing roles as to
super()__init__.

Change-Id: I22bf58dcbb5955eef7b37e76b909211f972c71ee

NetApp/manila,bswartz/manila,openstack/manila,vponomaryov/manila,vponomaryov/manila,NetApp/manila,bswartz/manila,openstack/manila