Support for cirros-0.4.0 password

Support for cirros-0.4.0 password

The password for cirros-0.4.0-x86_64-disk.img (and higher
cirros version images) is gocubsgo.
OpenstackOperation.robot takes cirros as username and
password as cubswin:).
So there is need to add two more arguments user=cirros and
password=gocubsgo.

The default passowrd will be changed in all library files once
we move to Openstack Stein on wards.

Signed-off-by: Srinivas Rachakonda <srinivas.rachakonda@gmail.com>
Change-Id: I92ac6c79caedc465412363d890d6e7c0c639d025