Build script to build web apps
    1: Add MemoryGame, hangonman as git submodule
    2: Add MemoryGame/manifest.json for MemoryGame build
    3: Add android build script android/android_build_app.py
    4: Add common build script make_webapp.py for both android and tizen
    5: Change hangonman/manifest.json local_path and icons path
         Because manifest.json will be outside app/src in crosswalk-demos

    How to use:
    Build all apps for both Tizen and Android
        python make_webapp.py
    Build specified app
        python make_webapp.py --app=MemoryGame
    Only build for Android
        python make_webapp.py --target=android
    Update Web Apps before build
        python make_webapp.py -u

    The build result will be under out directory