Add failedloginblocker app

Originally from https://github.com/alexkuhl/django-failedloginblocker
but that version isn't packaged as a python module, so vendoring to
allow us to test and integrate it.
Add tests for failedloginblocker
Remove failedloginblocker middleware

It's not actually doing anything
Whitespace
PEP8
Sort out imports
Make failedloginblocker timezone aware
Add middleware to handle failed login errors
Remove __init__.py from failedloginblocker
Add monitored model auth backend
Don't nest middleware so deeply
Fix failedloginblocker tests
Add missing return statement
Explain what's going on in the tests
Make failedloginblocker a module

:boom:
Update failedloginblocker docs
Don't count a blocked login as a failure
State how long logins are blocked for
RE-erganise base templates and includes
Remove old failedloginblocker