update path for test cases in ExampleImageLoaderRaw to use current pa…

…ge location as base. Fix when example is hosted on GitHub (#265)

example/exampleImageIdLoaderRaw.js

@@ -62,7 +62,8 @@
         }
     }
 
-    var baseUrl = '/example/displayedArea/test-cases/';
+
+    var baseUrl = window.location.pathname.substring(0, window.location.pathname.lastIndexOf('/')) + '/test-cases/';
 
     // register our imageLoader plugin with cornerstone
     cs.registerImageLoader('example', getExampleImage);