Bump the POI dependency to 3.11-beta2, and remove the Geronimo stax one which is no longer required by anything now we are on Java 1.6 TIKA-1380

git-svn-id: https://svn.apache.org/repos/asf/tika/trunk@1619108 13f79535-47bb-0310-9956-ffa450edef68