Fix importing config module and classmethod params

The Token/Endpoint options specify an instance method where the
expectation is a classmethod. This prevents the class being loaded from
config file or CLI.

The cfg module was not imported so loading plugins would raise an
AttributeError.

Change-Id: I33b4a8c181210d74d4779438afc1f918e06df85b
Merge "Fix importing config module and classmethod params"