Adding iOS push notification support

When passing an iOS push via redis, the following schema is expected:

```js
{
    "command" : {
        "command": "message",
        "device_token": user_device_token
    },
    "message" : {
        "event" : event_name,
        "data"  : object,
        "time"  : int
    }
}
```

The `data` object under `message` must have the following fields set:
- `message_text`
- `badge_count`