Add missing mailer app migration.

Signed-off-by: Roberto Rosario <roberto.rosario.gonzalez@gmail.com>

mayan/apps/mailer/migrations/0004_auto_20170714_2133.py

@@ -0,0 +1,20 @@
+# -*- coding: utf-8 -*-
+# Generated by Django 1.10.7 on 2017-07-14 21:33
+from __future__ import unicode_literals
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('mailer', '0003_auto_20170703_1535'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='usermailer',
+            name='default',
+            field=models.BooleanField(default=True, help_text='If default, this mailing profile will be pre-selected on the document mailing form.', verbose_name='Default'),
+        ),
+    ]