Add endpoints for approval node notifications

...and also add a migration file.

awx/main/migrations/0088_v360_approval_node_notifications.py

@@ -0,0 +1,28 @@
+# Generated by Django 2.2.4 on 2019-09-03 19:25
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('main', '0087_v360_update_credential_injector_help_text'),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name='organization',
+            name='approval_notifications',
+            field=models.ManyToManyField(blank=True, related_name='organization_approval_notifications', to='main.NotificationTemplate'),
+        ),
+        migrations.AddField(
+            model_name='unifiedjobtemplate',
+            name='approval_notifications',
+            field=models.ManyToManyField(blank=True, related_name='unifiedjobtemplate_approval_notifications', to='main.NotificationTemplate'),
+        ),
+        migrations.AlterField(
+            model_name='workflowjobnode',
+            name='do_not_run',
+            field=models.BooleanField(default=False, help_text='Indicates that a job will not be created when True. Workflow runtime semantics will mark this True if the node is in a path that will decidedly not be ran. A value of False means the node may not run.'),
+        ),
+    ]