Add a missing migration in the education app

website/education/migrations/0007_rename_answers_type.py

+from django.db import migrations, models
+
+
+def forwards_func(apps, schema_editor):
+    Exam = apps.get_model('education', 'Exam')
+
+    for exam in Exam.objects.all():
+        if exam.type == 'answers':
+            exam.type = 'exam_answers'
+            exam.save(update_fields=('type',))
+
+
+def reverse_func(apps, schema_editor):
+    Exam = apps.get_model('education', 'Exam')
+
+    for exam in Exam.objects.all():
+        if exam.type in ['exam_answers', 'partial_answers', 'resit_answers', 
+                         'practice_answers']:
+            exam.type = 'answers'
+            exam.save(update_fields=('type',))
+
+
+class Migration(migrations.Migration):
+    
+    dependencies = [
+        # Without this dependency we get multiple leaf nodes
+        ('education', '0006_auto_20171013_1535'),
+        # The real dependency
+        ('education', '0005_auto_20170906_2109'),
+    ]
+
+    operations = [
+        migrations.RunPython(forwards_func, reverse_func),
+    ]