Create MPR121_KEYPAD.INO

(*) 
modify the code from: Jim Lindblom
SparkFun Electronics
 created on: 1/6/10
 license: CC-SA 3.0
 
 Turns the MPR121 Touchpad into a phone keypad. Pressing a pad will
 print a 0-9, * or #.
 
 Hardware: 3.3V Arduino UNO R3
           SDA -> A4
           SCL -> A5
           IRQ -> 4

use arduino default wire library for low level I2C operation