Nagios event handlers for gluster services

  Adding gluster specific nagios event handlers which
can handle the gluster events from nagios.

 Master event handler is the one which will be
called by nagios to whenever a state change happens.
Internally this master event handler will call all
other gluster event handlers depending on the gluster
entity/service which is changing the state.

Added Ovirt Engine event handler to notify
nagios events to Ovirt Engine.

Signed-off-by: Ramesh Nachimuthu <rnachimu@redhat.com>