[server] upstart config change to start on network device up

For the upstart config make sure only start fwknopd after a non-loopback
network interface is brought up.  Also added a commented post-start script
to send an email whenever fwknopd is (re)started.

extras/upstart/fwknop.conf

@@ -5,11 +5,19 @@
 
 description	"fwknopd daemon"
 
-start on filesystem or runlevel [2345]
+start on (local-filesystems and net-device-up IFACE!=lo)
 stop on runlevel [!2345]
 
 respawn
 respawn limit 10 5
 umask 022
 
+### uncomment the post-start lines below if you want email notifications
+### whenever fwknopd is (re)started - be sure to edit the EMAIL_ADDR variable
+# post-start script
+#     HOST=`hostname`
+#     EMAIL_ADDR=you@domain.com
+#     mail -s "Starting fwknop on $HOST" $EMAIL_ADDR < /dev/null > /dev/null 2>&1
+# end script
+
 exec /usr/sbin/fwknopd -f