Update examples/strandtest/strandtest.pde

Just got rid of the SPI.h reference. It causes errors. thanks for the code. This is my first edit on gethub so please excuse my beginner nature. I was amazed that you made the code. I needed it for an ATTiny85 I programmed. Do you know why the Attiny does not accept SPI?  Is there a good reference material book or otherwise that would explain this stuff to me? My background is mechanical engineering. cheers, tom