Verify Minecraft Username 1.2
This is tested working in 2.0.18.x and 2.1.
Only validates server side on 2.1.
Note: If you want to validate the usernames server side on 188.8.131.52, you will have to add the missing RegisterValidation events in
$this->FireEvent('RegisterValidation'); on lines 1018, 1060, 1122, and 1188.