No default value for start date of membership

The admin form has an easily accessible "Today" button for date forms, so
there's no need to pre-fill the field with today's date.

coin/members/migrations/0007_auto_20141008_1107.py

@@ -0,0 +1,19 @@
+# -*- coding: utf-8 -*-
+from __future__ import unicode_literals
+
+from django.db import models, migrations
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('members', '0006_auto_20141008_1056'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='membershipfee',
+            name='start_date',
+            field=models.DateField(verbose_name='date de d\xe9but de cotisation'),
+        ),
+    ]

coin/members/models.py

@@ -276,7 +276,6 @@ class MembershipFee(models.Model):
     start_date = models.DateField(
         null=False,
         blank=False,
-        default=datetime.date.today,
         verbose_name='date de début de cotisation')
     end_date = models.DateField(
         null=False,