NUTCH-1837 Upgrade to Tika 1.6

git-svn-id: https://svn.apache.org/repos/asf/nutch/branches/2.x@1623571 13f79535-47bb-0310-9956-ffa450edef68
NUTCH-1840

git-svn-id: https://svn.apache.org/repos/asf/nutch/branches/2.x@1624472 13f79535-47bb-0310-9956-ffa450edef68