Switch from test/unit to minitest
Offer #has_capability? for libusb versions older than 1.0.9.
Add DevHandle#auto_detach_kernel_driver= of libusb-1.0.16.

Add capabilities introduced with libusb-1.0.16.

Use libusb_get_port_numbers preferred to now deprecated libusb_get_port_path.
Add new method port_numbers with alias to port_path.