Fix network.rb for XenServer Creedence Alpha

On the current alpha versions of xenserver the "ip addr" command skips "physical" interfaces, however "ip -d -s link" does list all interfaces.

This causes network.rb to fail on line 177 - because it tries to add state for an undefined interface.
The easiest fix is to create the iface[tmp_int] entry when we encounter a new interface during the parsing
of "ip -d -s link".

With this fix chef-client is again usable on XenServer.

Further debug output available on request.