Converted commander to use px4_posix calls

src/modules/commander/accelerometer_calibration.cpp

src/modules/commander/airspeed_calibration.cpp

src/modules/commander/commander.cpp

src/modules/commander/commander_helper.cpp

src/modules/commander/gyro_calibration.cpp

src/modules/commander/mag_calibration.cpp

src/modules/commander/module.mk