Add a gitkeep file to build directory to ensure it exists
Add a gitkeep file to build directory to ensure it exists

mozilla/MozDef,mpurzynski/MozDef,mozilla/MozDef,mpurzynski/MozDef,mpurzynski/MozDef,jeffbryner/MozDef,jeffbryner/MozDef,mozilla/MozDef,mpurzynski/MozDef,mozilla/MozDef,jeffbryner/MozDef,jeffbryner/MozDef