:fire: Drops Python 2.7, 3.4, and pypy and Django 1.11 support

[jefftriplett]

This PR drops support for no-longer supported versions of:

• Python 2.7
• Python 3.4
• PyPy (based on 2.7)
• Django 1.11 LTS

I left Django 2.0 and 2.1 in, but in they we could pull them too.