Merge pull request #21107 from edx/INCR-436

INCR-436 python3 compatibility

lms/djangoapps/grades/migrations/0001_initial.py

 # -*- coding: utf-8 -*-
-from __future__ import unicode_literals
+from __future__ import absolute_import, unicode_literals
 
-from django.db import migrations, models
-import coursewarehistoryextended.fields
 import django.utils.timezone
 import model_utils.fields
+from django.db import migrations, models
 from opaque_keys.edx.django.models import CourseKeyField, UsageKeyField
 
+import coursewarehistoryextended.fields
+
 
 class Migration(migrations.Migration):
 

lms/djangoapps/grades/migrations/0002_rename_last_edited_field.py

 # -*- coding: utf-8 -*-
-from __future__ import unicode_literals
+from __future__ import absolute_import, unicode_literals
 
 from django.db import migrations, models
 

lms/djangoapps/grades/migrations/0004_visibleblocks_course_id.py

 # -*- coding: utf-8 -*-
-from __future__ import unicode_literals
+from __future__ import absolute_import, unicode_literals
 
 from django.db import migrations, models
 from opaque_keys.edx.django.models import CourseKeyField

lms/djangoapps/grades/migrations/0007_add_passed_timestamp_column.py

 # -*- coding: utf-8 -*-
-from __future__ import unicode_literals
+from __future__ import absolute_import, unicode_literals
 
 from django.db import migrations, models
 

lms/djangoapps/grades/migrations/0008_persistentsubsectiongrade_first_attempted.py

 # -*- coding: utf-8 -*-
-from __future__ import unicode_literals
+from __future__ import absolute_import, unicode_literals
 
 from django.db import migrations, models
 

lms/djangoapps/grades/migrations/0009_auto_20170111_1507.py

 # -*- coding: utf-8 -*-
-from __future__ import unicode_literals
+from __future__ import absolute_import, unicode_literals
 
 from django.db import migrations, models
 

lms/djangoapps/grades/migrations/0011_null_edited_time.py

 # -*- coding: utf-8 -*-
-from __future__ import unicode_literals
+from __future__ import absolute_import, unicode_literals
 
 from django.db import migrations, models
 

lms/djangoapps/grades/migrations/0012_computegradessetting.py

 # -*- coding: utf-8 -*-
-from __future__ import unicode_literals
+from __future__ import absolute_import, unicode_literals
 
-from django.db import migrations, models
 import django.db.models.deletion
 from django.conf import settings
+from django.db import migrations, models
 
 
 class Migration(migrations.Migration):

lms/djangoapps/grades/migrations/0014_persistentsubsectiongradeoverridehistory.py

 # -*- coding: utf-8 -*-
 # Generated by Django 1.11.16 on 2018-11-27 20:53
-from __future__ import unicode_literals
+from __future__ import absolute_import, unicode_literals
 
+import django.db.models.deletion
 from django.conf import settings
 from django.db import migrations, models
-import django.db.models.deletion
 
 
 class Migration(migrations.Migration):