Item11267: Restructure save handler

It's only needed in the tasks web, so don't load it unless required.

Also change the call to ->log() to use writeDebug instead.  The newlines
written here exposed the bug in the logrotate code.

git-svn-id: http://svn.foswiki.org/trunk@17755 0b4bb1d4-4e5a-0410-9cc4-b2b747904278