Update the address of the NAT probe server

IP address is now an EC2 elastic IP so we should be able to move it even
if we have to shut down the server.

src/nat/probe.ts

@@ -8,7 +8,7 @@ import logging = require('../logging/logging');
 // We keep this running on Amazon EC2 and the source
 // may be found here:
 //   https://github.com/uProxy/uproxy-probe/blob/master/python-src/probe-server.py
-var TEST_SERVER = '54.68.73.184';
+var TEST_SERVER = '52.34.126.245';
 var TEST_PORT = 6666;
 
 var log :logging.Log = new logging.Log('probe');