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
Seems like missing `case "PATCH":` here. Probably that's why updates are not synced with the app. 

Some background:
Updates are performed with PATCH. PUT is more like "replace". You provide id and a document - fortune replaces full document with the new one (or inserts if this id cannot be found) while PATCH is able to run atomic updates. As PUT is more likely to be update rather than insert i suggest to default it to "update" and leave it for now. Afaik - there's no `wasNew` flag in `after` hooks to tell apart new document from updated one.