[Botkit] trigger controller events

Sending text messages is only one part of dialogue.
Equally important is events emitted by client side of connection.

For example I want to trigger `hello` event of [Sockets connector](https://github.com/howdyai/botkit/blob/380fc164ed5238d7cf8f5ebf4eac348440ecbfa6/lib/Sockets.js#L62) to make bot send the greeting before user starts typing.
And I want to send a custom message type from frontend to make my bot perform certain action.
```js
#me
{
"type": "payment",
"card_number": "4444********1111",
"cv2": "***",
"expiry": "12/19"
}
```