openlmi-storage: Add polkit integration.
Review Request #1924 - Created July 23, 2014 and submitted
Add polkit integration. The polkit actions are taken from storaged and udisks, just with org.openlmi.storage prefix. This allows us to experiment with existing authorization schemes and identify problems in storaged and udisks. The storage provider itself still runs as root, but is asks polkit to authorize each action. Since polkit authorizes processes and not users, we must spawn a little helper process under UID of the remote user to check the authorization, see lmi.storage.util.polkit module. There is one fork and several execs involved in each policy check.