Add caching and standard timezone indicator. Support different variants of automatically including timezones in text representations.


git-svn-id: https://svn.calendarserver.org/repository/calendarserver@13707 e27351fd-9f3e-4f54-a53b-843176b1656c
Calendar data comparisons must not implicitly include timezones.


git-svn-id: https://svn.calendarserver.org/repository/calendarserver@13708 e27351fd-9f3e-4f54-a53b-843176b1656c
Make sure non-standard timezones are not stripped from calendar data in the db or when returned to clients.


git-svn-id: https://svn.calendarserver.org/repository/calendarserver@13709 e27351fd-9f3e-4f54-a53b-843176b1656c
badcua no longer used.


git-svn-id: https://svn.calendarserver.org/repository/calendarserver@13710 e27351fd-9f3e-4f54-a53b-843176b1656c