Merge pull request #1301 from linovia/bugfix/tutorial_for_python3

Fix tutorial's step 1 for Python 3

docs/tutorial/1-serialization.md

@@ -183,9 +183,9 @@ At this point we've translated the model instance into Python native datatypes.
 
 Deserialization is similar.  First we parse a stream into Python native datatypes... 
 
-    import StringIO
+    from rest_framework.compat import BytesIO
 
-    stream = StringIO.StringIO(content)
+    stream = BytesIO(content)
     data = JSONParser().parse(stream)
 
 ...then we restore those native datatypes into to a fully populated object instance.