Minor improvements proposal

[benoitbryon]

Hi,

I started to work on django#502, but then I discovered the auth-cbv branch... So, let's contribute to it!

Here is a proposal for some minor improvements in the auth-cbv branch:

• moved some implementation logic into methods (such as LoginView.set_test_cookie) so that, if one wants to inherit from LoginView (that's my use case), it's easier to perform fine-grained overrides.
• converted is_valid_redirect() to a validator.
• used success_url in LoginView too.

Then, here are some notes about the branch status...

• We currently pass (i.e. fail silently) when LoginView or LogoutView have empty success_url. Is that ok? I mean, shouldn't we raise ImproperlyConfigured instead?
• We don't validate settings.LOGIN_REDIRECT_URL or views' success_url. Is that ok? I know it's safer than input from the request, but shouldn't we use at least some URLValidator?
• contrib/auth/views.py changed since last "rebase" (actually a merge). Could be useful to update.

[benoitbryon]

contrib/auth/views.py changed since last "rebase" (actually a merge). Could be useful to update.

I said it because I couldn't run the tests on my computer when switching to the auth-cbv branch, whereas tests run successfully with Django's master branch:

>>> git checkout 2b09e576210ab8761310e6daa494bf5016618d65
>>> ./runtests.py --settings=test_sqlite --failfast
Traceback (most recent call last):
  ...
  TypeError: 'class Meta' got invalid attribute(s): index_together

I'm sorry, I didn't run the tests :(