Converter 'zip2html' should handle any type of ZIP files

Currently, XML extension and java code of converter zip2html only support ZIP files with MIME type application/zip, it should support the other MIME types the java library used by the Nuxeo Platform is supporting.
FYI this is now more obvious than before as this converter is used by the new Web UI to display a preview of the ZIP file when navigating to a document.

Previous Nuxeo versions most likely suffer the same bug.