Using node-maxcdn w/ maxconf.js over maxcurl.

Hey,

> ##### WARNING: this is untested, as I don't have the hardware. Please clone my repo and verify before merging.

So `node-maxcdn` is designed for exactly this purpose. I understand you using `maxcurl` for the simple `~/.maxcdn.yml` configuration, so I wrote and released https://github.com/MaxCDN/maxconf.js, which abstracts the configuration methodology from the maxcli apps to a simple node lib. I then did a slight refactor here.

Pros:
* one less setup setup &ndash; a.k.a. self contained
* removing `child_process.exec`, which is always a point of fragility.
* being pure node, means better portability &ndash; (i.e.) you don't have to change your `maxcurl` binary when changing OS or platform