Fix chart image.

Author: Lipata

HTMLSamples/data-chart/edit-chart-items-with-knockout.html

@@ -36,7 +36,7 @@
         .legend-container {  width: 300px; margin-top: 10px; }
             .legend-container .title { font-weight: bold; font-size: 14px; margin-bottom: 10px; }
             .legend-container .legend { float: left; width: 48px; height: 48px; margin: 2px 5px 5px 0; padding: 0;
-                background-image: url(../../../../images/data-chart/music-controls-sprite.png); background-repeat: no-repeat; 
+                background-image: url(https://igniteui.github.io/help-samples/images/data-chart/music-controls-sprite.png); background-repeat: no-repeat; 
                 border: 1px solid #535353; zoom: 50%; }
             .legend-container .add { background-position: -337px 0px; }
             .legend-container .delete { background-position: -384px 0px; }
@@ -63,7 +63,7 @@
                 .btn-container .btn-add-end:hover { background-position: -336px -50px; }
             .legend-container .btn-pause { background-position: -96px 0px; opacity: 0.5 }
             .legend-container button { float: left; width: 48px; height: 48px; margin: 2px 5px 5px 0; padding: 0; border: none; cursor: pointer; padding: 0;
-                background-image: url(../../../../images/data-chart/music-controls-sprite.png); background-repeat: no-repeat; 
+                background-image: url(https://igniteui.github.io/help-samples/images/data-chart/music-controls-sprite.png); background-repeat: no-repeat; 
                 border: 1px solid #535353; zoom: 50% }
         .legend-container span { font-size: 12px; }
         #barColumnChart { margin-top: 20px; }