adding missing # before comment in BrickPi.py

Hi.
I'm not a python dev.
But I tried using BrickPi for the first time today and got an error when running the examples.
The error said there's a problem in line 35 in BrickPi.py.
So I took a look and it seems like in the latest commit some text that's not code was not prefixed with a #.
My change is to add this comment identifier.
After I did this the error message was gone.