pylightning - allow unicode symbols in the description to be passed a…

…s-is to the daemon

addresses issue #2753.

Formatting the JSON with the default parameters will escape the unicode
symbols in a way that c-lightning won't allow, leading to an exception.

contrib/pylightning/lightning/lightning.py

@@ -172,7 +172,7 @@ def __init__(self, socket_path, executor=None, logger=logging, encoder_cls=json.
         self.next_id = 0
 
     def _writeobj(self, sock, obj):
-        s = json.dumps(obj, cls=self.encoder_cls)
+        s = json.dumps(obj, ensure_ascii=False, cls=self.encoder_cls)
         sock.sendall(bytearray(s, 'UTF-8'))
 
     def _readobj(self, sock, buff=b''):