Added image scrollbar to viewports (LT-20)

Added image scrollbar to viewports (LT-20)

Packages/viewerbase/client/components/viewer/imageControls/imageControls.js

@@ -0,0 +1,14 @@
+Template.imageControls.events({
+    'input #imageSlider': function(e) {
+        // Using the slider in an inactive viewport
+        // should cause that viewport to become active
+        var slider = $(e.currentTarget);
+        var newActiveElement = slider.parents().eq(2).siblings('.imageViewerViewport').get(0);
+        setActiveViewport(newActiveElement);
+
+        // Subtract 1 here since the slider goes from 1 to N images
+        // But the stack indexing starts at 0
+        var newImageIdIndex = parseInt(slider.val(), 10) - 1;
+        switchToImageByIndex(newImageIdIndex);
+    }
+});