Set SPICS pin to output in begin()

It took me a while to figure this out, but the SPICS pin is not necessarily initialized to output when the arduino starts. Explicitly making it an output in the begin() method saves the library user from having to set the pin as output in their code (which they may not know they need to do, since it is not in the example code).
Merge pull request #2 from woodward1/patch-2

Set SPICS pin to output in begin()