piwigoexport : Support the new Piwigo Web API 2.4

Reorganize the interface (now, looks like Picasa/Facebook plugin
interface)
Retrieve the title, the comment, the date and the authors with
KPImageInfo API
Remove useless options in the dialog box
Replace the old Piwigo icon by the new one
Replace the old Piwigo logo in the dialog box

M +- -- piwigoexport/icons/hi16-action-piwigo.png
M +- -- piwigoexport/icons/hi22-action-piwigo.png
M +- -- piwigoexport/icons/hi32-action-piwigo.png
M +- -- piwigoexport/icons/hi48-action-piwigo.png
M +- -- piwigoexport/icons/hisc-action-piwigo.svgz
M +- -- piwigoexport/piwigo_logo.png