Docs/tutorial import fixes. Refs #2296

docs/api-guide/serializers.md

@@ -22,11 +22,13 @@ The serializers in REST framework work very similarly to Django's `Form` and `Mo
 
 Let's start by creating a simple object we can use for example purposes:
 
+    from datetime import datetime
+    
     class Comment(object):
         def __init__(self, email, content, created=None):
             self.email = email
             self.content = content
-            self.created = created or datetime.datetime.now()
+            self.created = created or datetime.now()
 
     comment = Comment(email='leila@example.com', content='foo bar')
 
@@ -61,10 +63,10 @@ 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...
 
-    from StringIO import StringIO
+    from django.utils.six import BytesIO
     from rest_framework.parsers import JSONParser
 
-    stream = StringIO(json)
+    stream = BytesIO(json)
     data = JSONParser().parse(stream)
 
 ...then we restore those native datatypes into a dictionary of validated data.

docs/tutorial/1-serialization.md

@@ -161,8 +161,6 @@ 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...
 
-    # This import will use either `StringIO.StringIO` or `io.BytesIO`
-    # as appropriate, depending on if we're running Python 2 or Python 3.
     from django.utils.six import BytesIO
 
     stream = BytesIO(content)