Category fixes

added prefix support
fix strict developer mode errors

Signed-off-by: Tim Rüther <tim@holosystems.de>
fix strict developer mode errors

Signed-off-by: Tim Rüther <tim@holosystems.de>
set image as default (image,thumbnail,small_image)
add Exception logging for files

Signed-off-by: Tim Rüther <tim@holosystems.de>