Change MemoryGame/manifest.json:local_path to app/index.html

    Currently, the game source is a submodule from 01.org,
    and it contains some un-needed files under [src],
    what crosswalk needed html related sources are all under [app].
    It's hard to submodule only one folder which we needed,
    And to make build script simple, current solution is:
    Change our manifest.json to route local_path to app/index.html, to make build succeed
    and the un-needed files will also be included.
    
    For better solution need to be discussed and redesigned.