Refactoring of ADC reading on AAPS

Implemented general command IPC_CMD_GET_ADC
for both current and voltage measurements.
One byte that tells which type of measurement has
been done is trasfered in the response packet.

-Refactoring
Cleanup up main()

Moved all execution of functionality
to new file cmd_exec.c
Removed ISR for SW1 and SW2
Refactoring max1168