Highlight use of permissions alnog with authentication
Add `Unauthenticated` exception.
Add docs for 401 vs 403 responses
Use correct status code
Use correct status code
Use two seperate exceptions - `AuthenticationFailed`, and `NotAuthenticated`

Cleaner seperation of exception and resulting HTTP response.
Should result in more obvious error messages.
Merge with master
Remove OAuth2 from docs
Implementing 401 vs 403 responses
Merged to latest master
Added PATCH HTTP method to the docs
Add failed testcase for fieldvalidation
Add possible solution for field validation error
WWW-Authenticate responses
Merge branch 'master' into unauthenticated_response

Conflicts:
	docs/api-guide/authentication.md
Merge pull request #416 from tomchristie/unauthenticated_response

Unauthenticated requests - 401 vs 403 responses
Add twitter share button to index page.
Update release notes.
Add separate test for failed custom validation
Improve validate_<fieldname> fix