Initial check-in of the Booth Cluster Ticket Manager.

Booth manages the ticket which authorizes one of the cluster sites located in
geographically dispersed distances to run certain resources. It is designed to
be an add-on of Pacemaker, which extends Pacemaker to support geographically
distributed clustering.

Booth includes an implementation of Paxos and Paxos Lease algorithm, which
guarantees the distributed consensus among different cluster sites. One
development goal of the Paxos implementation is to be flexible enough so that
it can also be used by some other projects which need Paxos.

Signed-off-by: Jiaju Zhang <jjzhang@suse.de>