Add app.json for heroku deployment and its auto deploy button

[bhaveshAn]

Actual Behaviour

Currently, there is no auto deployment button of Heroku and no app.json present.

Expected Behaviour

Adding app.json and thus auto-deployment button for Heroku.

Steps to reproduce it

Add steps to reproduce bugs or add information on the place where the feature should be implemented. Add links to a sample deployment or code.

LogCat for the issue

Provide logs for the crash here

Screenshots of the issue

Where-ever possible attach a screenshot of the issue.

Would you like to work on the issue?

Yes