Added hotkey support to viewerbase

Packages/viewerbase/client/components/studyBrowser/thumbnails/thumbnails.html

@@ -0,0 +1,5 @@
+<template name="thumbnails">
+    {{#each thumbnails}}
+        {{ >thumbnailEntry }}
+    {{/each}}
+</template>

Packages/viewerbase/client/components/studyBrowser/thumbnails/thumbnails.js

@@ -0,0 +1,15 @@
+Template.thumbnails.helpers({
+    thumbnails: function() {
+        var study = this;
+        var stacks = createStacks(study);
+        
+        var array = [];
+        stacks.forEach(function(stack, index) {
+            array.push({
+                thumbnailIndex: index,
+                stack: stack
+            });
+        });
+        return array;
+    }
+});