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-lesiontracker/lib/getTimepointObject.js

@@ -0,0 +1,18 @@
+/**
+ * Returns timepoint object given a specified imageId
+ *
+ * @param imageId
+ * @returns {*|{}} Timepoint object
+ */
+getTimepointObject = function(imageId) {
+    var study = cornerstoneTools.metaData.get('study', imageId);
+    if (!study) {
+        return;
+    }
+
+    return Timepoints.findOne({
+        studyInstanceUids: {
+            $in: [study.studyInstanceUid]
+        }
+    });
+};