First cut at refactoring servos/sensor.

Extracted out classes for the light sensor and the
servos.
Fixed a defect in the readValues method.

Was reading the LDR values into local variables instead of the
instance variables. Also changed the delay value in the main
loop and added serial outs of the diff values.
Changed servo pins and refactored *dot calculation.

Preparing for the inclusion of the BLE shield which eats up
digital pins 9 and 10. Moved the servo pins to 6 and 7. Also
created a new method to get both the *dot values at the same
time rather than requiring two calls.