Create a form for logging in a user
Add login/ URL and supporting view logic

The login/ URL supports GET, POST and DELETE operations.
Add some tests for the login/ URL
Add factory for creating a User

The authentication and authorization system utilizes User objects quite heavily.
Test the ability to log in and log out
Fix incorrect LOGIN_URL in settings.py
Remove spurious test.

I'm not even sure what the removed test is good for.
Require user to be logged in to fetch most pages

Also: update unit tests. Make sure the test client is logged in before each test
case is run.
Test "login guards"

Add tests that ensure the user must be logged in to GET certain paths.
Add log out form