Merge branch 'master' of http://github.com/theojulienne/mongoengine into v0.4

mongoengine/base.py

@@ -255,7 +255,10 @@ class TopLevelDocumentMetaclass(DocumentMetaclass):
         # Set up collection manager, needs the class to have fields so use
         # DocumentMetaclass before instantiating CollectionManager object
         new_class = super_new(cls, name, bases, attrs)
-        new_class.objects = QuerySetManager()
+        
+        # Provide a default queryset unless one has been manually provided
+        if not 'objects' in dir(new_class):
+            new_class.objects = QuerySetManager()
 
         user_indexes = [QuerySet._build_index_spec(new_class, spec)
                         for spec in meta['indexes']] + base_indexes