Match .carousel-inner specificity to beat styles

'.carousel ing' was replaced with '.carousel-inner > .item > img' in
3.0 and now loses the specificity war. To make carousel images 500px
tall, match specificity to make carousel.css win.

carousel/carousel.css

@@ -40,7 +40,7 @@ body {
 .carousel .item {
   height: 500px;
 }
-.carousel img {
+.carousel-inner > .item > img {
   position: absolute;
   top: 0;
   left: 0;