Add debug messages and fix for running with Node 0.10.32.

This pull request makes connect-injector work with Node 0.10.32 and closes #11. Also adds debug messages and removes the clunky header rewriting (after reading the Node HTTP code it turned out that you just have to not set `content-length` to get chunked encoding by default).

The actual fix was to re-set to the original `res.write` when ending the response.