Provide a default for shown_on_other_platforms now it's now nullable

apps/map/migrations/0042_auto_20180328_1122.py

@@ -0,0 +1,20 @@
+# -*- coding: utf-8 -*-
+# Generated by Django 1.11.6 on 2018-03-28 11:22
+from __future__ import unicode_literals
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('map', '0041_auto_20180328_0616'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='casestudy',
+            name='shown_on_other_platforms',
+            field=models.BooleanField(default=True, help_text='Tick the box if you would like us to show this case study on other social media platforms', verbose_name='Show on other platforms?'),
+        ),
+    ]

apps/map/models.py

@@ -963,6 +963,7 @@ class CaseStudy(models.Model):
     shown_on_other_platforms = models.BooleanField(
         verbose_name=_("Show on other platforms?"),
         help_text=_("Tick the box if you would like us to show this case study on other social media platforms"),
+        default=True
     )
 
     # 4.4.1