use LDAPUser and ldapdb in profile page

Currently I am using anon LDAP queries to parse data.
In the future when we will implement a secondary password I'll add user
LDAP queries.
addition of helper bash scripts for development
python2 only, add --traceback
Introduce initial code for two-phase auth support.

This commit adds a simple NoOTPDevice model that currently serves
the purpose of responding successfully to any request. The login view
has been extended with proper OTP device setup and initial verification
support.
Introduce a dummy token input.
Support TOTP with database storage (temporarily).

A dedicated database model is used to store the secrets. If user does
not have a secret, it is assumed that he disabled OTP.
Introduce 'otp-setup', to set TOTP up.
Support displaying QRCode for TOTP URI.
Support SOTP recovery keys.
Revoke used tokens atomically.

This should prevent replay attacks on TOTP and SOTP.
Re-use TOTPDevice for handling 'OTP disabled'.

There's no point in having a special device that checks if TOTP secret
is set. Let's just do that in TOTPDevice.
Merge pull request #50 from tampakrap/bin

addition of helper bash scripts for development
Merge pull request #48 from mgorny/otp

First part of OTP support
Remove Modelbackend, it is useless
Sync tests/settings with settings/

Bring back django_auth_ldap in INSTALLED_APPS so we can run its tests here directly
Merge pull request #51 from tampakrap/remove_modelbackend

Remove modelbackend
Rename common/testcase to common/test_helpers

It will get more helper functions/classes for the tests
Add okupy.common.test_helpets.set_request

It is replacement to okupy.tests.unit.views.anon_request
Among the various improvements, it replaces OTPMiddleware().process_request
with request.user.is_verified, which fakes is_verified() function for User obj
switch to set_request in the tests
Remove useless tests, they are covered by django_auth_ldap testsuite already