Fix deprecated use of REQUEST and only read the GET request

RemovedInDjango19Warning: `request.REQUEST` is deprecated, use
`request.GET` or `request.POST` instead.

Author: stephane

webstack_django_sorting/middleware.py

@@ -1,22 +1,21 @@
 def get_field(self):
     try:
-        field = self.REQUEST['sort']
+        field = self.GET['sort']
     except (KeyError, ValueError, TypeError):
         field = ''
     return (self.direction == 'desc' and '-' or '') + field
 
 def get_direction(self):
     try:
-        return self.REQUEST['dir']
+        return self.GET['dir']
     except (KeyError, ValueError, TypeError):
         return 'desc'
 
 
 class SortingMiddleware(object):
     """
-    Inserts a variable representing the field (with direction of sorting)
-    onto the request object if it exists in either **GET** or **POST**
-    portions of the request.
+    Inserts a variable representing the field (with direction of sorting) onto
+    the request object if it exists in **GET** portions of the request.
     """
     def process_request(self, request):
         request.__class__.field = property(get_field)