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

LesionTracker/client/components/app/app.js

@@ -0,0 +1,46 @@
+const studylistContentId = 'studylistTab';
+const viewerContentId = 'viewerTab';
+
+// Define the ViewerData global object
+// If there is currently any Session data for this object,
+// use this to repopulate the variable
+Template.app.onCreated(() => {
+    ViewerData = Session.get('ViewerData') || {};
+});
+
+Template.app.events({
+    'click .js-toggle-studyList'() {
+        const contentId = Session.get('activeContentId');
+
+        if (contentId !== studylistContentId) {
+            switchToTab(studylistContentId);
+        } else {
+            switchToTab(viewerContentId);
+        }
+    }
+});
+
+Template.app.helpers({
+    studyListToggleText() {
+        const contentId = Session.get('activeContentId');
+        
+        // If the Viewer has not been opened yet, 'Back to viewer' should
+        // not be displayed
+        const viewerContentExists = !!Object.keys(ViewerData).length;
+        if (!viewerContentExists) {
+            return;
+        }
+
+        if (contentId === studylistContentId) {
+            return 'Back to viewer';
+        } else if (contentId === viewerContentId) {
+            return 'Study list';
+        }
+    },
+
+    onStudyList() {
+        return (Session.get('activeContentId') === 'studylistTab');
+    }
+});
+
+Session.set('defaultSignInMessage', 'Tumor tracking in your browser.');