New node version and content-type fix

I updated my repo to use a later version of node.js. The streamReadable class changed in node 0.10 and requires calling the read() function or using the previous 'data' event handler. I opted for the new 'readable' handler and the read() function.

I also only send "Content-type" on non-GET requests. I added "Accept" for application/json and that got me past a problem where xml was being returned instead of JSON on a GET request.

I don't know if you want to, but since the nodejs version is moving I imagine that you might want to update the version of mldb as well.

Let me know if you have any questions or if I'm misunderstanding something.

Thanks
Steve