Merge pull request #33 from mcharleb/cmake-mc-2

CMakeLists.txt

Makefile

cmake/nuttx/px4_impl_nuttx.cmake

cmake/posix/builtin_commands.cpp_in

cmake/posix/configs/config-posix-sitl.cmake

cmake/posix/posix-sitl-simple.cmake

cmake/posix/px4_impl_posix.cmake

cmake/posix/px4_target_impl.cmake

src/CMakeLists.txt

src/firmware/posix/CMakeLists.txt

src/include/build_git_version.h

src/modules/simulator/CMakeLists.txt

...platforms/posix/drivers/airspeedsim/meas_airspeed_sim.cpp

src/systemcmds/CMakeLists.txt

src/systemcmds/topic_listener/CMakeLists.txt