Use MAC of eth0 if power_address has not been defined. (LP: #912476)

Index: cobbler-2.2.2/templates/power/power_ether_wake.template
===================================================================
--- cobbler-2.2.2.orig/templates/power/power_ether_wake.template	2011-11-15 12:32:16.000000000 -0500
+++ cobbler-2.2.2/templates/power/power_ether_wake.template	2012-02-01 12:58:21.579803287 -0500
@@ -1,3 +1,6 @@
+#if $power_address is None or $power_address == ""
+    #set $power_address = "%s" % $mac_address_eth0
+#end if
 if [ -x /sbin/ether-wake ]; then
 	/sbin/ether-wake -i eth0 "$power_address"
 elif [ -x /usr/bin/powerwake ]; then
