Added documentation, refactored, and fixed some bugs

The purpose of this pull request was to clean up node-supervisord-eventlistener and add some documentation.  Please review at your convenience.

* Added README.md file
* Added comments/documentation to `index.js`
* Now using Node-preferred method to inherit prototype from `EventEmitter`
* Fixed up some code style issues to maintain consistency
* Fixed possible edge-case issues when parsing headers/payload
* Push to version 0.1.0

Thanks for your work on this library!  I hope that you will accept this pull request and push to NPM.  Please let me know if you have any questions or concerns.  I'd be happy to fix any issues.