Convert Forms to Formtastic

[moonglum]

This will make the code more readable. Also, using a form partial, it can be easily re-generated when something changes in the model.

[moonglum]

From our old guidelines:

To create forms, we use Formtastic. So create your model including migrations and then run rails g formtastic:form MODELNAME --haml --partial, so the generated partial file will be written in haml Syntax. For more information on the Syntax, go to the github page. If you change your model later on, just run the command again and only the partial for the form will be updated.