PDFBOX-2456: add test for encrypt decrypt compare embedded file, as suggested by Ralf Hauser; refactored his code

git-svn-id: https://svn.apache.org/repos/asf/pdfbox/trunk@1635818 13f79535-47bb-0310-9956-ffa450edef68
PDFBOX-2456: add test file with embedded file created by Ralf Hauser

git-svn-id: https://svn.apache.org/repos/asf/pdfbox/trunk@1635820 13f79535-47bb-0310-9956-ffa450edef68
PDFBOX-2465: throw exception instead of NPE for malformed PDFA xmp

git-svn-id: https://svn.apache.org/repos/asf/pdfbox/trunk@1635828 13f79535-47bb-0310-9956-ffa450edef68