preload originality_reports on grade_summary

(also cache the plugin checks)

Change-Id: I711910adcc8da70a7475a4efc6c6f3a25af582db
Reviewed-on: https://gerrit.instructure.com/106155
Tested-by: Jenkins
Reviewed-by: Jeremy Stanley <jeremy@instructure.com>
Product-Review: James Williams  <jamesw@instructure.com>
QA-Review: James Williams  <jamesw@instructure.com>

Author: maneframe

app/presenters/grade_summary_presenter.rb

@@ -57,11 +57,17 @@ def editable?
   end
 
   def turnitin_enabled?
-    @context.turnitin_enabled? && assignments.any?(&:turnitin_enabled)
+    unless defined?(@turnitin_enabled)
+      @turnitin_enabled = @context.turnitin_enabled? && assignments.any?(&:turnitin_enabled)
+    end
+    @turnitin_enabled
   end
 
   def vericite_enabled?
-    @context.vericite_enabled? && assignments.any?(&:vericite_enabled)
+    unless defined?(@vericite_enabled)
+      @vericite_enabled = @context.vericite_enabled? && assignments.any?(&:vericite_enabled)
+    end
+    @vericite_enabled
   end
 
   def observed_students
@@ -182,6 +188,10 @@ def submissions
       .where("assignments.workflow_state != 'deleted'")
       .where(user_id: student).to_a
 
+      if vericite_enabled? || turnitin_enabled?
+        ActiveRecord::Associations::Preloader.new.preload(ss, :originality_reports)
+      end
+
       visible_assignment_ids = AssignmentStudentVisibility.visible_assignment_ids_for_user(student_id, @context.id)
       ss.select!{ |submission| visible_assignment_ids.include?(submission.assignment_id) }