issue #63: fix comments

app/models/review.rb

@@ -52,7 +52,9 @@ class Review < ApplicationRecord
 
   validates_presence_of :user, :reviewable
   validates_inclusion_of :reviewable_type, in: %w(LearningObject Collection), message: 'Only LearningObjects and Collections are reviewable.'
-  validates_uniqueness_of :user, scope: [:reviewable_id, :reviewable_type]
+  
+  # users should be able to comment multiple times
+  # validates_uniqueness_of :user, scope: [:reviewable_id, :reviewable_type]
 
   accepts_nested_attributes_for :review_ratings