Fortune Websockets

I've added a plugin that adds an `afterWrite` hook to fortune to notify users of creation, update and removal of documents on fortune via websockets.

In order to do this, a client can connect via socket io (currently on port 4000);

```js
var resourceName = 'person';
var livePersons = io('http://localhost:4000' + '/' + resourceName);
livePersons.on('add', function(data) {
  // do something when a person is added
});
livePersons.on('update', function(data) {
  // do something on update;
});
livePersons.on('delete', function(data) {
 // do something on delete;
});
```

## To Do:
- [x] Add websockets plugin with notifications for CUD (users don't need to be notified when an user Reads)
- [x] Better tests
- [x] Add namespace support instead of rooms? 
- [ ] Decide on what the payload of the event should be for Create, Update and Delete.
- [ ] Obtain / decide on port number for socket.io to listen to - currently it is set to 4000
Hm.. Yeah, thought it's here already. Basically we expose the route already in `.exposeResourceDefinitions` but it definitely makes sense to keep things consistent for internal and external users