Added missing import to django.contrib.formtools.preview from [4259].…

… Thanks, Vadim Macagon

git-svn-id: http://code.djangoproject.com/svn/django/trunk@4260 bcc190cf-cafb-0310-a4f2-bffc1f526a37

django/contrib/formtools/preview.py

@@ -48,6 +48,7 @@ def done(self, request, clean_data):
 from django.core.exceptions import ImproperlyConfigured
 from django.http import Http404
 from django.shortcuts import render_to_response
+from django.template.context import RequestContext
 import cPickle as pickle
 import md5