Interactive support

[confact]

Tested and work on my local env.

Added:

• update method to update a message directly on slack
• combined methods for interactive respond in remote, server and bot to forward the request data from the webhook

fixes #28

[confact]

Thanks for your feedback.

I have no excuse for missing tests. I will fix that. I have totally missed the call method so I will use that instead, my bad.

[lazyatom]

Apologies for the delay with this; I've merged a cleaned up version of commits here: https://github.com/exciting-io/slack-bot-server/commit/f8c68ff98dbce82a69a80b85e7fe72378ece81d6