Django 1.8 fails with an ImproperlyConfigured exception when `fields` or
`exclude` isn't set:

```
class Meta:
 fields = '__all__'
 ```

 on all descendents of ModelForm.

 Omitting this is deprecated in 1.7:

 https://docs.djangoproject.com/en/1.7/topics/forms/modelforms/#selecting-the-fields-to-use

Change-Id: Ie42c94c436dc06e15629b5ed289973c631d6bdf3
diff --git a/xos/admin.py b/xos/admin.py
index f679e4e..f4bf20d 100644
--- a/xos/admin.py
+++ b/xos/admin.py
@@ -13,6 +13,7 @@
 
     class Meta:
         model = ExampleService
+        fields = '__all__'
 
     def __init__(self, *args, **kwargs):
         super(ExampleServiceForm, self).__init__(*args, **kwargs)
@@ -64,6 +65,7 @@
 
     class Meta:
         model = ExampleTenant
+        fields = '__all__'
 
     creator = forms.ModelChoiceField(queryset=User.objects.all())