Bug in function set_payload

[jferdelyi]

In the file urrobot.py the function set_payload (line 121) need to have '[' instead of '('

Before

if cog:
            cog = list(cog)
            cog.insert(0, weight)
            prog = "set_payload({}, ({},{},{}))".format(*cog)

After

if cog:
            cog = list(cog)
            cog.insert(0, weight)
            prog = "set_payload({}, [{},{},{}])".format(*cog)