This change implements the sahara.service.sessions module with the basic
session cache object. It also adds the authentication plugin from the
keystonemiddleware into the context for rest transactions.
It also migrates the keystone client utility functions to use the new
session methodology. The trust module has been accordingly fixed to make
greater use of authentication objects instead of client objects.
* adding auth plugin to context
* adding sessions module
* adding test for sessions
* adding keystonemiddleware base auth plugin object to context on api
call
* adding keystone session to sessions module
* refactoring keystone client to use sessions
* adding keystone methods to retrieve auth plugins, tokens, and service
catalog
* changing sahara.service.trusts to use new keystone methods
* fixing trust tests to fit new authentication methodologies
Change-Id: I65ed4b4dcee8752bf4e66ef9e47305ff408d8d5d
Partial-Implements: bp keystone-sessions
f240d55ac5