message: travis: clean up examples as well
diff: @@ -10,6 +10,7 @@ make fix_style
  (cd example/fly_mission && mkdir build && cd build && cmake -DCMAKE_BUILD_TYPE=Debug .. && make)
  (cd example/offboard_velocity && mkdir build && cd build && cmake -DCMAKE_BUILD_TYPE=Debug .. && make)
  make clean
  +git clean -dfx
  make BUILD_TYPE=Release run_unit_tests -j4
  make install
  