Modified JS code to handle changes in express 3

I modified the code in heat_tracer.js to correctly handle change in express 3, which no more inherits from http and therefore we need to setup the http server separately to make the whole thing work. Change breaks initialization of app, which can no more use express.createServer and as well fails on socket.IO where the express object cannot be passed. 
Also the verbosity of socket.IO seems rather too big, so I made the output a bit quieter. We can still tune this if needed but, the initial state seems a bit too verbose to me.