added coward ghost behavior

commit 631ec6712b7032d3f4c1cf6204e5dfd476732c1d
Author: Leon Ho <neonaleon.dev@gmail.com>
Date:   Mon Sep 1 00:41:52 2014 +0800

    missed committing cpp file

commit 27616fc8d6690bf9917f143ee90fb07099385fc3
Author: Leon Ho <neonaleon.dev@gmail.com>
Date:   Mon Sep 1 00:37:22 2014 +0800

    fixed issue where timer doesn't countdown if it didn't receive update

commit 0213e15b1845ee2f9b37676c84efed2bb278bf7a
Author: Leon Ho <neonaleon.dev@gmail.com>
Date:   Mon Sep 1 00:15:55 2014 +0800

    added ghost coward variant behavior

commit 291d7f49b4da027f118c2594aa2fb6ac3aa7cf6b
Author: Leon Ho <neonaleon.dev@gmail.com>
Date:   Sat Aug 30 23:08:37 2014 +0800

    refactored AI code to use Monster.

commit fd939599379a7363d1f16e4d0430f6a9c3d42603
Author: Leon Ho <neonaleon.dev@gmail.com>
Date:   Sat Aug 30 21:51:09 2014 +0800

    refactored AI code to use GameObject
fixed wrong variable name