add debug output in i2c array writing

Author: frankalicious

Adafruit_PWM_Servo_Driver/Adafruit_I2C.py

@@ -39,6 +39,9 @@ def writeList(self, reg, list):
     "Writes an array of bytes using I2C format"
     try:
       self.bus.write_i2c_block_data(self.address, reg, list)
+      if (self.debug):
+        print("I2C: Wrote %s to register 0x%02X" % 
+              (' '.join('0x%02X' % (i) for i in list), reg))
     except IOError, err:
       print "Error accessing 0x%02X: Check your I2C address" % self.address
       return -1