For work plugin you 
1) Edited the MimeMagic.php file to include:
    application/xml mm
2) add the following to /usr/share/mediawiki/includes/mime.types
    application/xml mm
3) Add 'mm' to the list of allowed file extensions, e.g.
$wgFileExtensions = array( 'png', 'gif', 'jpg', 'jpeg', 'wmz', 'mm' );
$wgFileExtensions = array( 'png', 'gif', 'jpg', 'jpeg', 'mm' ); // files for download
$wgEnableUploads = true; 
$wgStrictFileExtensions = false; // IF false, don't check  $wgFileExtensions
$wgVerifyMimeType = false; // off controll MIME - type