Added South migrations
Added safedelete to `LoginCode`

When a LoginCode is deleted actualy is not removed from the
database but marked as deleted.

This is done using https://github.com/makinacorpus/django-safedelete
Added tox

https://testrun.org/tox/latest/
Fixed failing migrations

Migrations where fixed so they use the correct user model depending on
the running environment
Merge branch 'south-1' into softdelete

Conflicts:
	requirements.txt
	setup.py
Updated django-safedelete requirement
Maked softdelete optional

Using `NOPASSWORD_SOFTDELETE` settings is posible to choose from
`django.db.models.Model` or `SoftDeleteMixin` as `LoginCode` base class
Merge pull request #21 from tucarga/softdelete

Added softdelete to `LoginCode`