Changed http to node-rest-client and added proxy settings.

Hello,

First off, big thank you for this! 
It totally fitted our need.
I made some changes to support proxies.

I changed the use of http to node-rest-client.
This supports proxy authentication and it also parses the data to a json object.
Resulting in less code for that :)

Please take a look and merge/give feedback on how we can merge this.

Kind regards,
Henk vd Brink