Fix tests with errors/failures

[sreichel]

In #443 i have skipped a few tests that are broken and have to be reviewed:

• Zend_Filter_Encrypt_OpensslTest::testInvalidDecryption
• Zend_Pdf_ProcessingTest::testInfoProcessing
• Zend_Pdf_ProcessingTest::testModify
• Zend_Pdf_ProcessingTest::testPageCloning