The tests weren't using keep_blank_values when calling
urlparse.parse_qs, so any empty values were just ignored and
couldn't be tested properly. With this change, tests can verify
query parameters that have no value (for example, ?no_catalog on
the v3 auth request).
bp auth-token-use-client
Change-Id: Iafcb952c81ca7bd2acab4383687c36ec68a838d2