Binary pip distributions for Windows and Mac

[sbarzowski]

Binary distribution for Linux in pip is quite tricky – PyPI has special requirements - https://www.python.org/dev/peps/pep-0513/ (intended to ensure compatibility across distros) and doesn't accept wheels which were just built with python setup.py bdist_wheel.

We can quite easily provide Mac an Windows binary distribution and I expect it to lower the total number of issues encountered by the users (building from source on Mac and Windows caused issues regularly for C++ Jsonnet).