update pinnings so that we don't need to compile numpy anymore (1.16 doesn't have wheels for py3.8)

while at it, use pip-compile to generate a fully pinned requirements.txt from requirements.in

runtime.txt: Upgrade to the current Python 3.8

glob is a standard library module

Pin Python version to 3.5

This pins the version of Python to the one that fits the versions pinned
in the requirements.txt file.

Specified version doesn't have wheels for 3.7,
causing super slow builds

2.x doesn't have 3.7 wheels, and requires a specific
version of Cython to build on 3.7

Create LICENSE

Be good reproducible citizens