License headers for php files

webadmin/backupconfirm.php

webadmin/backuprestore.php

webadmin/blocking.php

webadmin/bridges.php

webadmin/dynamicdns.php

webadmin/emailproxy.php

webadmin/formatconfirm.php

webadmin/installapp.php

webadmin/installappconfirm.php

webadmin/installappfailed.php

webadmin/language.php

webadmin/newuser.php

webadmin/password.php

webadmin/removeapp.php

webadmin/removeappconfirm.php

webadmin/removeuserconfirm.php

webadmin/reset.php

webadmin/restoreconfirm.php

webadmin/search.php

webadmin/settings_datserver.php