Update dependencies to libusb1
    
    The runtime requirement was switched a while ago to a choice of
    libusb-0.1 and libusb-1.0.  Since nowadays the 0.1 API is provided by a
    compat shim on top of 1.0, better to just use that directly.  The -devel
    package is no longer required to build though since no binding is built;
    the library is loaded through ctypes.
    
    Also, run the tests in accordance with Python packaging guidelines.