Update tests for python 3.6, django 1.10+

[tony]

Help catch us up to latest django and python versions.

Let's see what travis says about this first.

[tony]

https://travis-ci.org/hellysmile/django-activeurl/builds/257108895?utm_source=github_status&utm_medium=notification

The current state of what we're testing against is out of control.

We should bump up the minimum Django version and Python version.

Currently, we're testing Django 1.3 to 1.9 (and 1.9 is from github tarball since a package probably wasn't on pypi at the time)

Bump to django 1.8+?

https://github.com/django-extensions/django-extensions is for Django 1.8 or later. That seems like a fair thing to test again.

Django 1.8 LTS EOL is April 2018.

Just for CI / tests

Though, this should effect CI only. Since this plugin is simple, older versions will likely keep working.

@hellysmile Thoughts on deprecating old versions, at least from CI?

[coveralls]

Coverage remained the same at 100.0% when pulling bac899f on develtech:update-tests into dc0c979 on hellysmile:master.

[coveralls]

Coverage remained the same at 100.0% when pulling bac899f on develtech:update-tests into dc0c979 on hellysmile:master.

[hellysmile]

Need to exclude not supported django versions for 3.6

[tony]

let's follow up with this and #22 AM tomorrow my time (CDT). if you have any other things (code smells/nitpicks/mistakes I made) let me know and I'll tend to them too.