Update django to 2.1.5

[pyup-bot]

This PR updates Django from 2.1.4 to 2.1.5.

Changelog

2.1.5

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

*January 4, 2019*

Django 2.1.5 fixes a security issue and several bugs in 2.1.4.

CVE-2019-3498: Content spoofing possibility in the default 404 page
-------------------------------------------------------------------

An attacker could craft a malicious URL that could make spoofed content appear
on the default page generated by the ``django.views.defaults.page_not_found()``
view.

The URL path is no longer displayed in the default 404 template and the
``request_path`` context variable is now quoted to fix the issue for custom
templates that use the path.

Bugfixes
========

* Fixed compatibility with mysqlclient 1.3.14 (:ticket:`30013`).

* Fixed a schema corruption issue on SQLite 3.26+. You might have to drop and
rebuild your SQLite database if you applied a migration while using an older
version of Django with SQLite 3.26 or later (:ticket:`29182`).

* Prevented SQLite schema alterations while foreign key checks are enabled to
avoid the possibility of schema corruption (:ticket:`30023`).

* Fixed a regression in Django 2.1.4 (which enabled keep-alive connections)
where request body data isn't properly consumed for such connections
(:ticket:`30015`).

* Fixed a regression in Django 2.1.4 where
``InlineModelAdmin.has_change_permission()`` is incorrectly called with a
non-``None`` ``obj`` argument during an object add (:ticket:`30050`).


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

Links

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