Refine regex that converts localip

The regex is converting 0.0.0.0 to the hosts localip, in most cases this
would be ok but on the overcloud in the metadata we have "ovs_range":
"10.0.0.0/8" which was getting converted to 1192.0.2.5/8.

Change-Id: If97107556a5b5de7c33049b6a798cc80b75b0cb8