ZP-273 #comment added ConfigContentParameters to IChanges, modified DiffBackend and all derived implementations, passing contentparameters also to ChangeMessage, DeleteMessage and SetReadFlag #time 2h 30m

git-svn-id: https://z-push.org/svn/z-push/trunk@1558 b7dd7b3b-3a3c-0410-9da9-bee62a6cc5b5