Add dbus and snmp notifier

Add dbus and snmp notifier

This is to send dbus events on major cluster events:
 - membership changes
 - application connect/dissconnet from corosync
 - quorum changes

dbus events can then be converted into snmp traps by foghorn or
corosync-notifyd can be run to directly send snmp traps.

Signed-off-by: Angus Salkeld <asalkeld@redhat.com>
Signed-off-by: Lon Hohberger <lhh@redhat.com>
Reviewed-by: Steven Dake <sdake@redhat.com>
Reviewed-by: Russell Bryant <russell@russellbryant.net>
Reviewed-by: Fabio M. Di Nitto <fdinitto@redhat.com>