Use classed based views for Django 1.11

[joshblum]

Fixes #80 for Django 1.11. For other versions of django a fix is needed in password_reset_confirm.html to add the tag <meta name="referrer" content="never"> and rel="noreferrer" should be added to the anchor tag in password_reset_email.html. I didn't see either of these templates in the repository, so it may be best to just warn users of the issue of potentially leaking the reset token through the Referrer header.

[coveralls]

Coverage decreased (-0.04%) to 90.37% when pulling dbdf7f66acfc94a7ea8d467e760a824fdaa3bd56 on joshblum:fix-referrer into 9a4adc6587d343f553f41e570508bc6f4ee0a5c5 on lambdalisue:master.