title: devise simple registration form
body: <p>The user fills in the form his email and password.
  After submiting the form, the user recieves an email, containing a activation link.
  After clicking on that link, he comes to an form, where he can fill out the rest of his data (login, gender, age and so on...), before he does'nt correctly fills out the form, he is not allowed to log in. </p>
  
  <p>How I can accomplish this scenario ?</p>