Add the IP address of the relay to the kite-offline query string

[BjarniRunar]

The most recent version of pagekite.py adds the IP address of the relay itself to the query string of the page displayed when a kite is offline. This is done to allow the offline page itself to give better feedback to the user if they are connected to "the wrong relay" for some reason.

This should be added to libpagekite as well.