Fix password update for users

Newer versions of keystone-client have changed the error message when an
invalid password is passed in. Update the logic so that puppet can
update passwords for users.

Change-Id: I090f7e2ee62ee189f37921c091fe51b6d587cd74
Closes-Bug: 1340447
(cherry picked from commit 1e21f7cbc28adbc28089b967c253f15e1e86d75d)
Merge "Fix password update for users" into stable/icehouse