[Knuth] Added support to non-default node server in /bin/node.sh

This is needed when you have more then one node in your machine.

Like, I have aways the last node release as default, but keep old versions for Cloud9 in the /usr/local/node/<version>/

So to ran cloud9 I just type today something like:

/usr/local/node/0.6/bin/node server.js .....

With the var in the /bin/cloud9.sh you just need to change the NODE param to the right node.js version bin and it will run smothly :)