Item12496: add isCacheable api



git-svn-id: http://svn.foswiki.org/trunk/core@16718 0b4bb1d4-4e5a-0410-9cc4-b2b747904278
Item12496: fixed use of uninizialized value



git-svn-id: http://svn.foswiki.org/trunk/core@16719 0b4bb1d4-4e5a-0410-9cc4-b2b747904278