Correct copyright notices

apps/calendar/ajax/activation.php

apps/calendar/ajax/createcalendar.php

apps/calendar/ajax/editcalendar.php

apps/calendar/ajax/newcalendar.php

apps/calendar/ajax/settimezone.php

apps/calendar/ajax/updatecalendar.php

apps/calendar/js/calendar.js

apps/calendar/settings.php

apps/calendar/templates/part.editcalendar.php

apps/calendar/templates/part.getcal.php

apps/calendar/templates/settings.php