Don't write the full traceback to stdout when read is impossible in t…

…he PyUSB mode, avoids polluting output with garbarge on Windows

src/inputs/usb_modem_pyusb.py

@@ -73,7 +73,8 @@ def read_loop(self):
 
                 except Exception:
 
-                    info('Connection from the mode closed: ' + format_exc())
+                    info('Connection from the USB link closed')
+                    debug('Reason for closing the link: ' + format_exc())
                     exit()
 
                 raw_payload += data_read