Allow arbitrary form fields

[marceloomens]

Generalise the form to allow arbitrary form fields (survey mode)

[marceloomens]

For the moment I've solved this by modularizing the form. The code base currently ships with:

• Email.elm
• Reportersrespond.elm

So long as the frontend framework supports my form fields, arbitrary form fields are supported. It would be nice to refactors some of the field rendering to some Fields.elm module.