Tilt #defines; maintenance

Added #define for the tilt register, simply logical AND these with the
tilt register result to get the corresponding state of the device.

check_shake() was renamed to check_tilt() for clarity.

Old I2C code was removed.
Tap detection enabled

Tap detection and shake detection enabled simultaneously. The tap
detection requires the highest sample rate (taking place on the
accelerometer) which will require a larger power draw. This may be
insignificant when compared to the other components.

Still, the larger sample rate makes the shake detection very sensitive.
The tap detection has built in debounce and debounce counters, but it
appears the shake detection does not. Therefore, we may need to debounce
it in software; count a threshold number of shake readings before we
consider it an actual shake.
Tap/Shake Demo with LEDS

Tapping the device (on x,y axis) should turn on green LEDs, shaking the
device will turn off the LEDs. A software debounce is implemented to
make the shaking less sensitive.

The overall sensitivity is a work in progress, the major problem being
that some shakes are also detected as taps, this will need to be worked
 out with some trial and error. The case could potentially help provide
a better "tap vector" too.