SLING-3858 : Avoid logging of exception if Tika is not available

git-svn-id: https://svn.apache.org/repos/asf/sling/trunk@1619036 13f79535-47bb-0310-9956-ffa450edef68
SLING-3858 : Avoid logging of exception if Tika is not available

git-svn-id: https://svn.apache.org/repos/asf/sling/trunk@1619037 13f79535-47bb-0310-9956-ffa450edef68