Merge pull request #15 from kurli/HexGL

Enable submodule and add manifest.json for HexGL demo app
Build script to build web apps
1: Add android build script android/android_build_app.py
2: Add common build script make_webapp.py for both android and tizen

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 and then build all of them
    python make_webapp.py -u

The build result will be under out directory