add comments migration to loopback script

loopbackMigration.js

@@ -160,15 +160,33 @@ var storyCount = dbObservable
   })
   .count();
 
+var commentCount = dbObservable
+  .flatMap(function(db) {
+    return createQuery(db, 'comments', {});
+  })
+  .withLatestFrom(dbObservable, function(comments, db) {
+    return {
+      comments: comments,
+      db: db
+    };
+  })
+  .flatMap(function(dats) {
+    return insertMany(dats.db, 'comment', dats.comments, { w: 1 });
+  })
+  .buffer(20)
+  .count();
+
 Rx.Observable.combineLatest(
   userIdentityCount,
   userSavesCount,
   storyCount,
-  function(userIdentCount, userCount, storyCount) {
+  commentCount,
+  function(userIdentCount, userCount, storyCount, commentCount) {
     return {
       userIdentCount: userIdentCount * 20,
       userCount: userCount * 20,
-      storyCount: storyCount * 20
+      storyCount: storyCount * 20,
+      commentCount: commentCount * 20
     };
   })
   .subscribe(
@@ -184,4 +202,4 @@ Rx.Observable.combineLatest(
       console.log('finished with ', count);
       process.exit(0);
     }
-);
+  );