Alt images, swift installation

Alternative images
Swift install
Fix for wrong version of cirros

it's not enough, due to the bug in stack.sh:

rgrep image_alt_ssh_user *
lib/tempest:    iniset $TEMPEST_CONFIG compute image_alt_ssh_user ${DEFAULT_INSTANCE_USER:-cirros}
635:devstack> rgrep image_ssh_user *
lib/tempest:    iniset $TEMPEST_CONFIG compute image_ssh_user ${DEFAULT_INSTANCE_USER:-cirros}
636:devstack>

So one needs to have it somehow defined. I''m going to to upstream patch set on that