add a __str__ implementation to APIException

Add a __str__ implementation to rest_framework.exceptions.APIException. This helps for logging raised exceptions. Thanks.

add regression tests for field Validators

pep8 and add issue no

fix formatting for python 2.6 and strings for python 3.2

Writable star source with instance

Fixed encoding parameter in QueryDict

authentication: allow all transport modes of access token in OAuth2Authentication

Update serializers.py

Uses nested serializer with parent object

Prevent iterating over a string that is supposed to be an iterable <==> Prevent read_only_fields = ('some_string)

Prevent iterating over a string that is supposed to be an iterable <==> Prevent read_only_fields = ('some_string)

RFC6750 describe three transport modes for access tokens when accessing a
protected resource:
- Auhthorization header with the Bearer authentication type
- form-encoded body parameter
- URI query parameter

This patch add support for last two transport modes.

Serializer fields section for 3rd-party packages

* Add new section to serializer fields page where we can list and link 3rd-party packages that provide more field types
* Add an entry for drf-compound-fields

Reintroduced url arguments in the urls for the tests.

Add SEARCH_PARAM and ORDERING_PARAM to settings

Unique constraint are validated even if the field is optional.

Fixes #1434

don't implicitly import provider.oauth2