Tweaked a few issues in the tutorial documentation.

docs/tutorial/1-serialization.md

@@ -191,7 +191,7 @@ Our `SnippetSerializer` class is replicating a lot of information that's also co
 In the same way that Django provides both `Form` classes and `ModelForm` classes, REST framework includes both `Serializer` classes, and `ModelSerializer` classes.
 
 Let's look at refactoring our serializer using the `ModelSerializer` class.
-Open the file `snippets/serializers.py` again, and edit the `SnippetSerializer` class.
+Open the file `snippets/serializers.py` again, and replace the `SnippetSerializer` class with the following.
 
     class SnippetSerializer(serializers.ModelSerializer):
         class Meta:

docs/tutorial/3-class-based-views.md

@@ -64,7 +64,7 @@ That's looking good.  Again, it's still pretty similar to the function based vie
 
 We'll also need to refactor our `urls.py` slightly now we're using class based views.
 
-    from django.conf.urls import patterns, url
+    from django.conf.urls import url
     from rest_framework.urlpatterns import format_suffix_patterns
     from snippets import views
 

docs/tutorial/4-authentication-and-permissions.md

@@ -177,7 +177,7 @@ In the snippets app, create a new file, `permissions.py`
             # Write permissions are only allowed to the owner of the snippet.
             return obj.owner == request.user
 
-Now we can add that custom permission to our snippet instance endpoint, by editing the `permission_classes` property on the `SnippetDetail` class:
+Now we can add that custom permission to our snippet instance endpoint, by editing the `permission_classes` property on the `SnippetDetail` view class:
 
     permission_classes = (permissions.IsAuthenticatedOrReadOnly,
                           IsOwnerOrReadOnly,)

docs/tutorial/5-relationships-and-hyperlinked-apis.md

@@ -106,6 +106,8 @@ If we're going to have a hyperlinked API, we need to make sure we name our URL p
 
 After adding all those names into our URLconf, our final `snippets/urls.py` file should look something like this:
 
+    from django.conf.urls import url, include
+
     # API endpoints
     urlpatterns = format_suffix_patterns([
         url(r'^$', views.api_root),