Fix method on manager's add command (#578)
diff --git a/shadowsocks/manager.py b/shadowsocks/manager.py
index b42ffa9df..2a1200c89 100644
--- a/shadowsocks/manager.py
+++ b/shadowsocks/manager.py
@@ -141,6 +141,8 @@ def _parse_command(self, data):
         command, config_json = parts
         try:
             config = shell.parse_json_in_str(config_json)
+            if 'method' in config:
+                config['method'] = common.to_str(config['method'])
             return command, config
         except Exception as e:
             logging.error(e)

All strings in JSON are encoded into bytes on `parse_json_in_str()`.
However, `config['method']` need a `str` rather than bytes.
