Refactor / rewrite

Hi @CMToups this pr. contains:
1. Rewrite into vanilla javascript - makes it easier for others to
contribute
2. Lean against the Node.js EventEmitter api
3. Implement client-side EventEmitter
4. Split client and server code
5. Remove dependencies on `underscore`, `coffee script` and
`event-emitter`
6. Rename into `EventEmitter` - Sorry, but feels better following the
node js api here?
7. Added some very basic tests

Reason I did this pr is because we could use this in the CollectionFS project - in an event package, @aldeed pointed at this package but it needed some work for us to rely on it. I hope its ok, this is pretty inversive I'm aware - But let me know what you think