Build a web chat interface for BenTen 

Currently Slack is the only channel supported by BenTen. Create a web chat interface. So users who want to build bots using BenTen feature need not be tied to Slack. Implement a web channel implementation similar to [Slack](https://github.com/intuit/benten/tree/master/benten-core/src/main/java/com/intuit/benten/channel/slack) channel.