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

In f383bd2973c58c5272504603e4f9dddd55c5bb68, oslo.context (2.2.0)
added roles support in the context itself. This passes roles to
super()__init__.

Change-Id: I0535728846006c0ad26c75a8fe36071e96e96f71

openstack/zaqar,openstack/zaqar,openstack/zaqar,openstack/zaqar