Added Adafruit Trinket sample.

Added a driver use sample for the Adafruit Trinket (based on AtTiny85).
The sample includes a Makefile, a main function, and hardware-specific
functions. Compiles successfully, but not yet tested on hardware.
Added programming target to Trinket sample.

Put a target in the Trinket sample's Makefile to run avrdude to program
the trinket with the sample binary. Also added a modified avrdude
configuration file with the proper settings for programming the Trinket.