Adding intial support for the img Stage Line DMX-1USB device. This is currently untested, but does compile. Hopefully closes #398

Try adding a libusb_set_configuration(usb_handle, 1) here. 

For bonus marks, print the result of libusb_get_configuration(usb_handle, &config_value) before calling set() . I'm going to guess it's 0 (unconfigured) .