[packagekit] Mime types checking

[Richard Hughes]

The daemon now checks the content type of files being passed to the
InstallFiles() method. If your backend does not specify a list of
content types in backend_get_mime_types(), then the file will be
refused and the method will fail with MimeTypeNotSupported. A typical
list of mime-types looks like this:
"application/x-rpm;application/x-servicepack".
This stops users using pkcon, or double clicking on .deb files on a
.rpm system (and vice versa) only for the backend to show an error or
explode into a million bits.

If you want to see the mime-type, as detected by gio (and thus
packagekitd), then do:

gvfs-info /path/to/file.foo -a "standard::content-type"

Please can you ensure that your backend has the correct content types
listed. Thanks.

Richard.