Add critical log level.


git-svn-id: https://svn.calendarserver.org/repository/calendarserver@12053 e27351fd-9f3e-4f54-a53b-843176b1656c
Get rid of restarted() on ChildStatus, also thge abandoned attribute.
When we get a "0" message, log a critical error is things are not as expected.


git-svn-id: https://svn.calendarserver.org/repository/calendarserver@12054 e27351fd-9f3e-4f54-a53b-843176b1656c
unused.


git-svn-id: https://svn.calendarserver.org/repository/calendarserver@12055 e27351fd-9f3e-4f54-a53b-843176b1656c
fixes for cleaning revision tables


git-svn-id: https://svn.calendarserver.org/repository/calendarserver@12056 e27351fd-9f3e-4f54-a53b-843176b1656c