Update django to 2.1.4

[pyup-bot]

This PR updates Django from 2.1.3 to 2.1.4.

Changelog

2.1.4

==========================

*December 3, 2018*

Django 2.1.4 fixes several bugs in 2.1.3.

Bugfixes
========

* Corrected the default password list that ``CommonPasswordValidator`` uses by
lowercasing all passwords to match the format expected by the validator
(:ticket:`29952`).

* Prevented repetitive calls to ``geos_version_tuple()`` in the ``WKBWriter``
class in an attempt to fix a random crash involving ``LooseVersion``
(:ticket:`29959`).

* Fixed keep-alive support in ``runserver`` after it was disabled to fix
another issue in Django 2.0 (:ticket:`29849`).

* Fixed admin view-only change form crash when using
``ModelAdmin.prepopulated_fields`` (:ticket:`29929`).

* Fixed "Please correct the errors below" error message when editing an object
in the admin if the user only has the "view" permission on inlines
(:ticket:`29930`).


==========================

Links

• PyPI: https://pypi.org/project/django
• Changelog: https://pyup.io/changelogs/django/
• Homepage: https://www.djangoproject.com/

[coveralls]

Coverage remained the same at 87.846% when pulling 5b9ef9b on pyup-update-django-2.1.3-to-2.1.4 into f6f1485 on master.