Fails with special characters: &, <, >, ', and "

[bishbashbackup]

Issue raised by Stuart Yeats on digipres.club. The script doesn't actively check the input it's given. As a result it fails when faced with processing special character: &, <, >, ', and "

Currently the script just tries to push these filenames with special characters through the xsl transform, which returns an error message and blank premis.xml document.