Edit Updated to work with django 1.10 and so on... using this https://docs.djangoproject.com/en/1.11/topics/http/middleware/#upgrading-middleware Edit2 Uploaded it to pypi: under "subdomains"
pip install subdomains
I'd recommend for django versions<=1.9 use django-subdomains from op, otherwise for django 1.10, 1.11 etc use my subdomains version
Subdomain helpers for the Django framework, including subdomain-based URL routing and reversing.
Full documentation can be found here: http://django-subdomains.readthedocs.org/
Tested on Python 2.6, 2.7, 3.4 and 3.5 on their supported Django versions from 1.4 through 1.9.