added a bit of sails friendly logging.
pi has a default high value when opening pins added a cb to write a low val

added a callback which disables shift register output.. writes a low
value to the sr_oe pin.
enabled the shift register output on enableZone

toggles the shift register outputs on after building the zones and such.
added optional callbacks to the gpio functions.
cleaned up a bit of whitespace
trying to get signt to work properly. still not successful