title: Use of + or . in the username part of email addresses
body: <p>Is there a way to make firebase authentication consider the following email addresses as equal for the purpose of signing up or logging in a (new) user?</p>
  <blockquote>
  <ul>
  <li>imauser@gmail.com</li>
  <li>imauser+test@gmail.com</li>
  <li>im.a.user@gmail.com</li>
  <li>im.a.user+test@gmail.com</li>
  </ul>
  </blockquote>