Flush needed for writes

[jemgoss]

In gpio.py, I had to add f.flush() after the write statements in order to get the pin state changed immediately. I believe this is because text streams are buffered by default. Alternative fix would be to use binary streams, but then some translation code would be necessary.

[gnarlie]

Thanks for the report. I've updated gpio.py with a flush - grab the latest and let us know if you see any more issues!