add mega and due compatible ArduinoISP sketches 

To fix https://github.com/arduino/Arduino/issues/2314

  The example present does not work with either
   Arduino Mega 2560 or Arduino Due

  Tested this 
   https://raw.githubusercontent.com/rsbohn/ArduinoISP/master/ArduinoISP/ArduinoISP.ino
   to work perfectly to turn Mega into a stk500v1 programmer

   And tested this
    https://raw.githubusercontent.com/PeterVH/ArduinoISP/due/ArduinoISP/ArduinoISP.ino
   to be compatible with Due to turn it into a stk500v1 programmer. (using the native port)

Signed-off-by: Arnav Gupta <championswimmer@gmail.com>