Correct path to jquery for admin password-change form

- The path to jquery for the admin form was incorrect so jquery was not being
loaded and the password change was never being submitted.
Add custom `changepassword` command to replace django built-in

This commit replaces Django's `manage.py changepassword` functionality.
This change is necessary because we hash the passwords client-side in the
Admin/Registration/Login pages using javascript and then authenticate
against that on the server. However, when using the commandline changepassword
the first hash does not happen which causes future authentications through
the web interface to fail
Merge pull request #439 from notthatbreezy/admin-password-fix

Fix Admin Password Change Bug