Fix: no need to decode() after redis client scan, so it will work for…

… both python2 and python3 (sonic-net#96)

The original code was tested in python2, which convert a str to a unicode str. It is working but not needed.

src/swsssdk/configdb.py

@@ -413,7 +413,7 @@ def __get_config(self, client, pipe, data, cursor):
             cur: poition of next item to scan
         """
         cur, keys = client.scan(cursor=cursor, match='*', count=self.REDIS_SCAN_BATCH_SIZE)
-        keys = [key.decode() for key in keys if key != self.INIT_INDICATOR]
+        keys = [key for key in keys if key != self.INIT_INDICATOR]
         for key in keys:
             pipe.hgetall(key)
         records = pipe.execute()