Skip test tokens

This patchset skips test_token test due to the change of 401 response
for an invalid token to a 404 response.  Keystone bug 1221889.

Once the change to keystone has been accepted, a subsequent patchset
will be proposed to tempest to renable the check and accept the new
404 HTTP status for the get_token call on invalid tokens.

related-bug: 1221889
Change-Id: I3c5691f5085e10e28b0f57505133ae3478167396
Merge "Skip test tokens"