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)
- [ ] 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
There's a bit confusing concept of pluralisation in fortune. Every resource is registered as singular word and and fortune pluralises it to get route name. So "person" becomes "people" and route to get people is `/people` not `/person` so it's better to follow this oddity here too. Plural form of resource is available on resource metadata object so it shouldn't be hard to switch to using plural form.  I guess it would be enough just to switch line 65 of this file to provide `resource.route` instead of `resource.name`.