Bump django from 1.11.26 to 1.11.27

Bumps [django](https://github.com/django/django) from 1.11.26 to 1.11.27.
- [Release notes](https://github.com/django/django/releases)
- [Commits](django/django@1.11.26...1.11.27)

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

requirements.txt

@@ -1,5 +1,5 @@
 coverage==5.0.3
-Django==1.11.26 # pyup: <2.0
+Django==1.11.27 # pyup: <2.0
 django-debug-toolbar==2.1
 docutils==0.16
 freezegun==0.3.13