Added autocomplete=off to Devise views that allow editing profile data (registration edit and password edit).

Firefox still seems to autocomplete passwords in these fields in some instances, but I think it's Firefox being opinionated, not much I can do about it.
Added Nokogiri gem to test group.

We will use it to parse html content in emails sent by Devise during testing. This way we can test that e.g. email confirmation emails contain the correct confirmation link.
Added acceptance test for the email change functionality.
Added acceptance test for the password change functionality.
Added acceptance test for the cancel account functionality.