python-pyusb: new package

PyUSB is a Python module that wraps libusb 1.0. (It can wrap other USB
libraries too, but I've hardcoded it for libusb as it seems the most
appropriate.)

(cherry picked from commit bc847600a9ab833164d0d6bd308023932eb4eec7)
python-usbtmc: new package

This Python package supports the USBTMC instrument control protocol for
controlling instruments over USB.

http://alexforencich.com/wiki/en/python-usbtmc/start
(cherry picked from commit 77000f7af019bacd3d3714c3c8ad8e995a446b6b)