Make contact form submission possible

We should change the form action in production mode to post to cosmos2.

That cosmos2 receiver is protected by rate limiting using a token, so the form submission needs some logic to collection a token and add it to the submitted form data. That code is already present on the Greenhost website, and ideally we would share that code, but I'm not sure how the existing jQuery-based code will interact with the react-created form, that may require some tweaking.