[AppDB] script to clean duplicate users

[Jonathan Ernst]

This script will remove duplicate users from the appdb (same email
address), give their data to the most recently logged user that has the
same email address and then fix the db structure so that it's not
possible anymore to have two time the same email address.

Usage:

1)chmod u+x ./clean.php
2)edit clean.php to set up the database connection (line 11 and 12)
3)./clean.php

(if php is not in /usr/bin/php you'll have to edit the first line too)