Add Support for Haven

[josolanes]

Describe the solution you'd like
I'd like to be able to control a chat bot in a private Haven chat server

[josolanes]

This has been completed

A new environment variable must also be populated:
CHAT_SERVICE_URL: The base address of your Haven server

You will also need to expose a port to support Haven's callback url functionality. The address of your ContainrBot (with /callback added) will need to be provided in your Haven bot Callback URL

Note: Haven does not allow IP, .local, or .internal URLs. More details in new library to support this change:
https://github.com/josolanes/Haven.DotNet#haven-bot-setup