ensure static network changes don't update DNS

`PEERDNS=no` ensures the DNS settings (from /etc/resolv.conf) are not
overwritten when we do an ifdown/ifup cycle to apply Vagrant's
changes.

templates/guests/redhat/network_static.erb

@@ -4,4 +4,5 @@ BOOTPROTO=static
 IPADDR=<%= options[:ip] %>
 NETMASK=<%= options[:netmask] %>
 DEVICE=eth<%= options[:interface] %>
+PEERDNS=no
 #VAGRANT-END