Returns extended MimeTypes.

def mimes(self):
        """
        Returns extended MimeTypes.
        """
        _mimes = MimeTypes(strict=False)
        _mimes.suffix_map.update({'.tbz2': '.tar.bz2'})
        _mimes.encodings_map.update({'.bz2': 'bzip2'})

        if cfg['CFG_BIBDOCFILE_ADDITIONAL_KNOWN_MIMETYPES']:
            for key, value in iteritems(
                    cfg['CFG_BIBDOCFILE_ADDITIONAL_KNOWN_MIMETYPES']):
                _mimes.add_type(key, value)
                del key, value

        return _mimes