Proper fix.


git-svn-id: https://svn.calendarserver.org/repository/calendarserver@13586 e27351fd-9f3e-4f54-a53b-843176b1656c
Fix tz functions to catch up to api changes.


git-svn-id: https://svn.calendarserver.org/repository/calendarserver@13587 e27351fd-9f3e-4f54-a53b-843176b1656c