Added persistent single-image measurments (length, ellipse) (LT-37, LT-156)

Packages/lesiontracker/both/collections.js

@@ -1,5 +1,6 @@
 Timepoints = new Meteor.Collection('timepoints');
 Studies = new Meteor.Collection('studies');
 Measurements = new Meteor.Collection('measurements');
+ImageMeasurements = new Meteor.Collection('imageMeasurements');
 
 WorklistSubscriptions = ['studies', 'timepoints'];