title: Manually unconfirm a user in devise, rails
body: <p>I'm trying to do something in my app, where if a user hasn't logged in within 90 days, their account will be set to unconfirmed, and they'll be emailed to re-confirm their email address.</p>
  
  <p>I know I can resend the email with this:</p>
  
  <pre><code>Devise::Mailer.confirmation_instructions(@user).deliver
  </code></pre>
  
  <p>I'm seeing these related fields in the schema - </p>
  
  <pre><code> t.string   "unconfirmed_email"
   t.string   "confirmation_token"
   t.datetime "confirmed_at"
   t.datetime "confirmation_sent_at"
  </code></pre>
  
  <p>Will setting them all to nil, and the unconfirmed email back to the regular email make this work?</p>