DuinOS: Small and Simple OS based on FreeRTOS

Hi LAVco,

I have changed the contents of boards.txt on the arduino mega 2560 to use the arduino.DuinOS core and also I have modified FreeRTOSConfig.h to include the AVR Atmega 2560 with the same settings as the 1280. Then I tried the simple blinking example, it would compile but the LED is not blinking when I upload it on the board.