Creating helpers to add classes in viewports and Layout Manager elements, so any app using ohif-viewerbase can style on its own

Packages/ohif-viewerbase/client/components/viewer/gridLayout/gridLayout.html

@@ -1,7 +1,7 @@
 <template name="gridLayout">
     <div id='imageViewerViewports'>
         {{#each viewport in viewports}}
-            <div class="viewportContainer" style="height:{{height}}%;width:{{width}}%;">
+            <div class="viewportContainer {{getClass @index}}" style="height:{{height}}%;width:{{width}}%;">
                 <div class="removable">
                     {{>imageViewerViewport (clone viewport)}}
                 </div>