Capital letters in mime types cause errors in gnome.

if capital leters are used in a mime type, gnome will throw assertion error:
(<unknown>:8328): libgnomevfs-CRITICAL **: file gnome-vfs-mime-info.c: line 916: assertion `!does_string_contain_caps (mime_type)' failed
when java web start goes to install it.
we should either install toLowerCase of the passed in string, or skip mime type entirely and show user and error dialog.