access to swift

According to http://docs.openstack.org/developer/ceilometer/install/manual.html

ceilometer needs access to swift with ResellerAdmin role (itself created by swift-proxy).

I'm not sure if this keystone_register method is the correct one, someone  with better keystone knowledge should check this.

See also https://bugzilla.novell.com/show_bug.cgi?id=844044