Add *png files needed by jquery-ui.css

Use this simple bash script to retrieve them:
sed -e 's/url.images./\n\n/g' ../jquery-ui.css | \
	sed -e 's/\.png./.png\n/g' | \
	grep png | \
	while read a; do \
		wget http://code.jquery.com/ui/1.10.3/themes/smoothness/images/$a;
  	done

Signed-off-by: Dimitris Aragiorgis <dimara@grnet.gr>