override cached_due_date with latest for versioned submissions

fixes CNVS-6869

reverts g/22303 and g/22305

Test Plan:
- make a submission
- change the due date on the submission's assignment
- the speedgrader should incorporate the change and be able to tell
  if the submission is overdue based on the new due date

Change-Id: I2604e0bde43a1f5970ee3a38813295be410f2212
Reviewed-on: https://gerrit.instructure.com/22480
Reviewed-by: Jacob Fugal <jacob@instructure.com>
Tested-by: Jenkins <jenkins@instructure.com>
QA-Review: Clare Strong <clare@instructure.com>
Reviewed-by: Brian Palmer <brianp@instructure.com>
Product-Review: Duane Johnson <duane@instructure.com>

app/models/assignment.rb

@@ -1124,7 +1124,6 @@ class Assignment < ActiveRecord::Base
       )
       if json['submission_history']
         json['submission_history'].map! do |version|
-          version.cached_due_date = sub.cached_due_date
           version.as_json(
             :include => {
               :submission_comments => { :only => comment_fields }

app/models/submission.rb

@@ -141,7 +141,8 @@ class Submission < ActiveRecord::Base
 
   simply_versioned :explicit => true,
     :when => lambda{ |model| model.new_version_needed? },
-    :on_create => lambda{ |model,version| SubmissionVersion.index_version(version) }
+    :on_create => lambda{ |model,version| SubmissionVersion.index_version(version) },
+    :on_load => lambda{ |model,version| model.cached_due_date = version.versionable.cached_due_date }
 
   def new_version_needed?
     turnitin_data_changed? || (changes.keys - [

lib/api/v1/gradebook_history.rb

@@ -30,9 +30,7 @@ module Api::V1
       student = opts[:student] || submission.user
       current_grader = submission.grader || default_grader
 
-      model = version.model
-      model.cached_due_date = submission.cached_due_date
-      json = submission_attempt_json(model, assignment, api_context.user, api_context.session, nil, course).with_indifferent_access
+      json = submission_attempt_json(version.model, assignment, api_context.user, api_context.session, nil, course).with_indifferent_access
       grader = (json[:grader_id] && json[:grader_id] > 0 && user_cache[json[:grader_id]]) || default_grader
 
       json = json.merge(

lib/api/v1/submission.rb

@@ -31,7 +31,6 @@ module Api::V1::Submission
     if includes.include?("submission_history")
       hash['submission_history'] = []
       submission.submission_history.each_with_index do |ver, idx|
-        ver.cached_due_date = submission.cached_due_date
         hash['submission_history'] << submission_attempt_json(ver, assignment, user, session, idx, context)
       end
     end