Stop returning correct password on api calls
Stop returning correct password on api calls

Captured invalid signature exception in authentication step, so that
the problem is not returning exception to user, revealing the real
password.
Fixes bug 868360.

Change-Id: Idb31f076a7b14309f0fda698261de816924da354

openstack-attic/melange,rajarammallya/melange,rajarammallya/melange,rackerlabs/melange,rackerlabs/melange,rackerlabs/melange,rajarammallya/melange,openstack-attic/melange,openstack-attic/melange