wrap the registration in a transaction

Sometimes when the creation of the person object fails the user get's
created anyway resulting in a user without a user profile.
By wrapping both the user and profile creation in a transaction the
user gets only created if the person profile worked as well.

django/didgeridoo/webshop/views.py

@@ -3,6 +3,7 @@ from django.shortcuts import get_object_or_404, render
 from django.contrib.auth.decorators import login_required
 from django.contrib.auth.models import User
 from django.contrib.auth.forms import UserCreationForm
+from django.db import transaction
 from webshop.models import (Article, Category, ArticleStatus, Person,
                             City, Picture, CartPosition, ShoppingCart)
 from webshop.forms import RegistrationForm, AddToCartForm
@@ -200,6 +201,7 @@ def registration(request):
             profile_form = RegistrationForm(request.POST)
             user_form = UserCreationForm(request.POST)
             if (profile_form.is_valid() and user_form.is_valid()):
+                with transaction.atomic():
                     pf = profile_form.cleaned_data
                     uf = user_form.cleaned_data
                     user = User.objects.create_user(uf['username'],