Inverting reset logic to work with SparkFun shield.

I can't find a schematic or info for Impeeduino so I'm not sure if you've got an inverted reset line? Seems odd. Please point me in that direction if available.

This pull request modifies the reset logic to work with the [SparkFun Imp Shield](https://www.sparkfun.com/products/11401). 

Code works great! Thanks for this. Bootloading a target Arduino from anywhere in the world is pretty spectacular!