[Enhancement] Multi Socket Support

Adding the ability to define multiple sockets on a single route. They are defined like:

```js
Ember.Route.extend({
  socketConfigurations: [{
    url: 'ws://localhost:8080'    
  }, {
    url: 'ws://localhost:8081',
    keepSocketAlive: false,
    binaryType: 'blob'
  }]
});
```

A simpler example is this:

```js
Ember.Route.extend({
  socketConfigurations: [{
    url: 'ws://localhost:8080'    
  }, {
    url: 'ws://localhost:8081'
  }]
});
```


```js
Ember.Controller.extend({
  actions: {
    onopen: function(event) {
      switch(event.url) {
         case 'ws://localhost:8080':
            // do something here
         case 'ws://localhost:8081':
           // do something else here
      }
    }
  }
});
```