This is similar to the LPD8806 sample, but uses the WS2812 driver
instead. The app configuration is a bit more finicky, so try to
provide helpful references. This could be made more beginner-friendly
with the addition of timing diagrams, etc., but this should be enough
for an experienced developer to use.
Signed-off-by: Marti Bolivar <marti.bolivar@linaro.org>