Contact form component problem

[lexoyo]

For now the contract form is made to use with formspree service by default. This service changed recently, they need the user to create an account, and the form needs to send the user id instead of the email like before.

Also there is Netlify forms now that we could support. And serverless forms, an open source alternative to formspree could be supported too.

So the contact form needs love again

• [ ] Make the component a Form tag in order to be able to add data-* attributes to it from Silex UI
• [ ] Support the new version of formspree
• [ ] Support Netlify forms
• [ ] Support serverless forms
• [ ] Update the docs