Make editable copies of Devise views with rails g devise:views
Allow admins to change password, email, or delete their account

Based on instructions at
https://github.com/plataformatec/devise/wiki/How-To:-Allow-users-to-edit-their-password

Devise is not set up to use the registrable module, so people cannot just
sign up online. A few extra changes in this commit are needed to let
people who have accounts change them.