Rename the .env_test to .env and fill the env vars:
APIAI_TOKEN=
APIAI_SESSION_ID=
The first one is an API.ai API key (Please get one by sign up with API.ai), and the second one is a session ID, which is an arbitrary string.
Or use this Heroku button to deploy to Heroku server. You just need to fill out the env vars with the API key and a session ID. No need to create an .env file.