Add deploy to heroku button for demos

[jettify]

It is very easy to deploy aiohttp app to heroku, and best part it is completely free. I think we should deploy few demos so users can play with apps.

Process is strait forward basically create Procfile with:

web: mlserve -c models.yml -H 0.0.0.0 -P $PORT

And deploy app with git:

$ heroku create
$ git push heroku master
$ heroku open

[Arfey]

something like this https://github.com/britter/spring-boot-heroku-demo?

[jettify]

Yeah, something like that. Helps to deploy project in no time basically.