Work on refactoring measurements out of Lesion Tracker package

- Removed AssociatedStudies Collection
- Measurement API is generated from configuration files
- Data exchange methods are defined in configuration

Packages/ohif-viewerbase/client/components/viewer/playClipButton/playClipButton.js

@@ -0,0 +1,8 @@
+Template.playClipButton.helpers({
+    isPlaying: function() {
+        return isPlaying();
+    },
+    disableButton() {
+        return hasMultipleFrames();
+    }
+});