Removes the requirement for swiftclient in swift-dispersion-report
and swift-dispersion-populate. To prevent a dependency on
keystoneclient and to avoid reinventing the wheel with an internal
keystoneclient, authentication with keystone is only supported if
swiftclient is available. If not, only auth v1 is supported.
The dependency in swift/container/sync.py has also been removed.
Implements: blueprint remove-swiftclient-dependency
Change-Id: I6ec3b3c85a67b9ab6eb04b90ffc16daf1600e8a7