Adding config file for Calunium with 8MHz RC oscillator.
Clear only the watchdog bit in MCUSR before resetting the watchdog.

Preserve other bits so that user application can find out reason for
reboot.
Adding supprt for ATmega1284 (non-P version).
Allow user to set AVRDUDE_OPTS to add to avrdude options (eg for -F).
Adding 8MHz and 16MHz conf files for Calunium.