Add fields to track member creation and edit datetimes (#48)

* Add created and updated fields.

bikeshop_project/registration/migrations/0004_auto_20170518_0332.py

@@ -0,0 +1,27 @@
+# -*- coding: utf-8 -*-
+# Generated by Django 1.10.4 on 2017-05-18 03:32
+from __future__ import unicode_literals
+
+from django.db import migrations, models
+import django.utils.timezone
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('registration', '0003_auto_20170215_0308'),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name='member',
+            name='created_at',
+            field=models.DateTimeField(auto_now_add=True, default=django.utils.timezone.now),
+            preserve_default=False,
+        ),
+        migrations.AddField(
+            model_name='member',
+            name='modified_at',
+            field=models.DateTimeField(auto_now=True),
+        ),
+    ]