Configure production deploy with Heroku

[lucasdavila]

Hello @phoemur !

Thanks for implementing this scraping API, I changed it a bit, so I could deploy it to Heroku and integrate with a Google Spreadsheet I created.

This PR contains the needed changes, to allow other devs to easily deploy this API to Heroku as well.

Basically I made these changes:

• Renamed required.txt to requirements.txt so Heroku could detect the python env automatically.
• Installed the gunicorn http server, to run the production API on Heroku.
• Added a Procfile which is required by Heroku to run the app.
• Translated the README file and documented the Heroku setup/deploy.

Hope you can accept this collaboration.

Thanks.