tools: notifier: Support snmp trap as a notification method.

See feature pages[1]

[1] http://www.ovirt.org/Features/engine-snmp

Change-Id: I0cd22d022ae535f45e046b09a2cbfadd837b465c
Bug-Url: https://bugzilla.redhat.com/show_bug.cgi?id=1032661
Signed-off-by: Mooli Tayer <mtayer@redhat.com>
Signed-off-by: Alon Bar-Lev <alonbl@redhat.com>