Correct servo rotation direction + add motor enable

[Felipe Machado]

Servo angle signs were wrong

This is the correct angle sign:

                     0 degrees (center)
                           |     
                           |     
   90 degrees (left)_______|_______ -90 degrees (right)

Servos pulses range from:
1000 us: -90 degrees ( 0 degrees) rightmost
1500 us: 0 degrees ( 90 degrees) center
2000 us: 90 degrees (180 degrees) leftmost

Also, motors should be stopped (disabled) when configuring the cameras or when no color filter is selected