Added new damaged,damaged_fullscreen and no_artwork_fullscreen images.
Modified the no_artwork and warning_fullscreen images.
Modified the image and image state area definitions as recommended by Jean-Yves Avenard.

new file:   images/damaged.png
new file:   images/damaged_fullscreen.png
modified:   images/no_artwork.png
new file:   images/no_artwork_fullscreen.png
modified:   images/warning_fullscreen.png
modified:   notification-ui.xml