requirements: use django-registration-redux to be compatible with 1.7

requirements.txt

@@ -2,7 +2,7 @@ Django==1.7
 django-ckeditor
 django-taggit
 git+https://github.com/toastdriven/django-haystack.git
-django-registration
+django-registration-redux
 django-jquery
 django-datetime-widget
 django-bootstrap-staticfiles