Fix cube server for node v0.10 

The `on('end')` is never being called, thus the evaluator is hanging and not returning any response to HTTP requests.

Relevant issues in node can be found here:
https://github.com/joyent/node/issues/4942

This is the commit which caused the change:
https://github.com/joyent/node/commit/327b6e3e1de88ba1db83142d53b3a57f0d06d519#lib/http.js