Removed Heroku settings.

The setup necessary for deploying to heroku has been completely removed
since the project is deployed to AppFog now.
Included Disqus as the comments management app.
Included Diqus API key.

As the API key shall be kept secret, a small workaround was needed in
order to load the key without hardcoding it in the settings file.
Included index.html and done all the coding necessary for its rendering.