Help with Pi Pan/Tilt Face tracker

Thank you, just tried this, it installed fine, then ran:

    sudo ./facetracker.py

Response now:

    Traceback (most recent call last):
      File "./facetracker.py", line 4, in <module>
        from pantile import *
      File "/home/pi/PanTiltFacetracker/pantilt.py", line 1, in <module>
        from Adafruit_PWM_Servo_Driver import PWM
       File "/home/pi/PanTiltFacetracker/Adafruit_PWM_Servo_Driver.py", line 11, in <module>
         class PWM:
       File "/home/pi/PanTileFacetracker/Adafruit_PWM_Servo_Driver.py", line 35, in PWM
         general_call_i2c = Adafruit_I2C(0x00)
       File "/home/pi/PanTiltFacetracker/Adafruit_I2C.py", line 36, in __init__
         self.bus = smbus.SMBus(busnum if busnum >= 0 else Adafruit_I2C.getPiI2CBusNumber())
    IOError: [Errno 2] No such file or directory