Adds task groups

* task now takes an optional keyword `group`
* added result_group()  and fetch_group()
* added group column to Success admin
* group column in searchable
* added `name` field to Schedules
* Scheduled tasks take schedule name as group

django_q/migrations/0005_auto_20150718_1506.py

@@ -0,0 +1,24 @@
+# -*- coding: utf-8 -*-
+from __future__ import unicode_literals
+
+from django.db import models, migrations
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('django_q', '0004_auto_20150710_1043'),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name='schedule',
+            name='name',
+            field=models.CharField(max_length=256, null=True),
+        ),
+        migrations.AddField(
+            model_name='task',
+            name='group',
+            field=models.CharField(max_length=100, null=True, editable=False),
+        ),
+    ]