Comment 3 for bug 495064

I've added an option to both the site options page, and the institution
settings page which allows you to choose whether users may delete
themselves or not. As a result, I've removed the check on registration
status of the institutions.

An institution can override the site preference in either direction, or
choose to follow the site default. If any one institution for the user opts
to disable user deletion, deletion is disabled for that user.

This change uses the institution preferences code I wrote recently (not in
master yet) so other than the database change required for the institution
preferences system itself, no other db change is required.

Located in git at http://git.luns.net.uk/mahara.git on branch
institution-selfdelete which is based upon the
institution-settings_noexample branch