python3 fix: make ListObject parameter order match unit test

ListObject used to set 'offset' and then 'limit', but the unit test assumes that the order is limit=...&offset=.... Since dict and kwargs are guaranteed to preserve insertion order in python3.6+ (https://www.python.org/dev/peps/pep-0468/), this change makes them insert in the same order as the test expects
Fixes
AssertionError: 'http://example.com/foo?offset=0&limit=10' != 'http://example.com/foo?limit=10&offset=0'

remoteobjects/listobject.py

@@ -193,9 +193,9 @@ def __getitem__(self, key):
         if isinstance(key, slice):
             args = dict()
             if key.start is not None:
-                args['offset'] = key.start
                 if key.stop is not None:
                     args['limit'] = key.stop - key.start
+                args['offset'] = key.start
             elif key.stop is not None:
                 args['limit'] = key.stop
             return self.filter(**args)