webrepl_cli.py: Set default SANDBOX to workaround esp8266 FS path issues.

Leading "/" doesn't work for path in esp8266 port curently.

Author: Paul Sokolovsky

webrepl_cli.py

@@ -11,7 +11,8 @@
 # Define to 1 to use builtin "websocket" module of MicroPython
 USE_BUILTIN_WEBSOCKET = 0
 # Treat this remote directory as a root for file transfers
-SANDBOX = "/tmp/webrepl/"
+SANDBOX = "."
+#SANDBOX = "/tmp/webrepl/"
 
 
 WEBREPL_FILE = "<3sBBBHQH64s"