Bug 7500 [FOLLOW-UP][Star ratings] Use CSS Sprites for faster page loading

Combines two star ratings sprites into one and makes
the corresponding CSS changes. The two original images
have been removed.

To test, view star ratings on search results and the detail page.
Try setting star ratings on the detail page.

Signed-off-by: Chris Cormack <chrisc@catalyst.net.nz>

koha-tmpl/opac-tmpl/prog/en/css/jquery.rating.css

@@ -1,9 +1,11 @@
 /* jQuery.Rating Plugin CSS - http://www.fyneworks.com/jquery/star-rating/ */
 div.rating-cancel,div.star-rating{float:left;width:15px;height:15px;text-indent:-999em;cursor:pointer;display:block;background:transparent;overflow:hidden}
-div.rating-cancel,div.rating-cancel a{background:url(../../images/delete.gif) no-repeat 0 -16px}
-div.star-rating,div.star-rating a{background:url(../../images/star.gif) no-repeat 0 0px}
-div.rating-cancel a,div.star-rating a{display:block;width:16px;height:100%;background-position:0 0px;border:0}
+div.rating-cancel,div.rating-cancel a{background:url(../../images/star-ratings-sprite.png) no-repeat 0 -49px}
+div.star-rating,div.star-rating a{background:url(../../images/star-ratings-sprite.png) no-repeat 0 0px}
+div.rating-cancel a{display:block;width:16px;height:100%;background-position:0 -49px;border:0}
+div.star-rating a{display:block;width:16px;height:100%;background-position:0 0px;border:0}
 div.star-rating-on a{background-position:0 -32px!important}
+div.rating-cancel.star-rating-hover a{background-position:0 -65px}
 div.star-rating-hover a{background-position:0 -16px}
 /* Read Only CSS */
 div.star-rating-readonly a{cursor:default !important}