Migrate VAT rate to use a single date field rather than datetime.

There is never any need to track the time as VAT rate hardly ever changes and will always do so at midnight. We were already assuming this anyway but it was generating loads of warnings/errors.

This will break your local VAT rate database if using sqlite, but it is tested with postgres and works fine.

RIGS/migrations/0025_auto_20160331_1302.py

@@ -0,0 +1,26 @@
+# -*- coding: utf-8 -*-
+# Generated by Django 1.9.4 on 2016-03-31 12:02
+from __future__ import unicode_literals
+
+import django.core.validators
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('RIGS', '0024_auto_20160229_2042'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='profile',
+            name='username',
+            field=models.CharField(error_messages={'unique': 'A user with that username already exists.'}, help_text='Required. 30 characters or fewer. Letters, digits and @/./+/-/_ only.', max_length=30, unique=True, validators=[django.core.validators.RegexValidator('^[\\w.@+-]+$', 'Enter a valid username. This value may contain only letters, numbers and @/./+/-/_ characters.')], verbose_name='username'),
+        ),
+        migrations.AlterField(
+            model_name='vatrate',
+            name='start_at',
+            field=models.DateField(),
+        ),
+    ]