PDFBOX-2460: add check that strong encryption is installed

git-svn-id: https://svn.apache.org/repos/asf/pdfbox/trunk@1634993 13f79535-47bb-0310-9956-ffa450edef68
PDFBOX-2423: Fix for transparency groups and pages with non-origin crop boxes

git-svn-id: https://svn.apache.org/repos/asf/pdfbox/trunk@1634999 13f79535-47bb-0310-9956-ffa450edef68