Update : This repo was made at the time when Dialogflow was known as API.AI. You will have to use Dialogflow APIs V1 in the console to make it work, that said. this repo is no longer maintained by the creators.
You can simply chose to Build it yourself from scratch using this Tutorial.
OR...
Follow these steps below
git clone https://github.com/sushantshekhar20/bot-api.ai.git
cd bot_api.ai
npm install
node bin/www
Edit the Chat Flow from public/javascripts/convo.js