Custom Queues config

Added ability to specify the queue connection and the actual queue to write errors to via config

```
'queue' => [
        /*
        |--------------------------------------------------------------------------
        | Connection
        |--------------------------------------------------------------------------
        |
        | Set the connection to use from the list in config/queue.php
        |
        */
        'connection' => '',

        /*
        |--------------------------------------------------------------------------
        | Queue
        |--------------------------------------------------------------------------
        |
        | Set the queue to use for raven
        |
        */
        'queue' => ''
   ]
```