Fix test__makefile_ref on Windows using a test-time optional dependency on psutil. appveyor installs this dep.

Trying latest batch magic from https://github.com/ogrisel/python-appveyor-demo/tree/master, claims 3.5 support

it does not exist here. Instead, manually copy all build commands into appveyor.yml.

Note, ECHO without arguments prints "ECHO is off." on Windows, so it should not be used.

all scripts are from from https://github.com/ogrisel/python-appveyor-demo

see also https://packaging.python.org/en/latest/appveyor.html