Fix formatting of digest response string


git-svn-id: https://svn.calendarserver.org/repository/calendarserver@13494 e27351fd-9f3e-4f54-a53b-843176b1656c
Use newer twext which has digest auth fix


git-svn-id: https://svn.calendarserver.org/repository/calendarserver@13495 e27351fd-9f3e-4f54-a53b-843176b1656c