remove old ajax files

apps/calendar/ajax/activation.php

apps/calendar/ajax/choosecalendar.php

apps/calendar/ajax/createcalendar.php

apps/calendar/ajax/deletecalendar.php

apps/calendar/ajax/deleteevent.php

apps/calendar/ajax/editcalendar.php

apps/calendar/ajax/editevent.php

apps/calendar/ajax/editeventform.php

apps/calendar/ajax/gettimezonedetection.php

apps/calendar/ajax/guesstimezone.php

apps/calendar/ajax/importdialog.php

apps/calendar/ajax/moveevent.php

apps/calendar/ajax/newcalendar.php

apps/calendar/ajax/newevent.php

apps/calendar/ajax/neweventform.php

apps/calendar/ajax/resizeevent.php

apps/calendar/ajax/settimeformat.php

apps/calendar/ajax/settimezone.php

apps/calendar/ajax/timeformat.php

apps/calendar/ajax/timezonedetection.php