[Suggest] Make assets key the same with its full path

[Kin Wang]

In generated js, I found this:

lib.as3_PixiAnimate.assets = {
    "a1": "images/a1.png",
    "a2": "images/a2.png",
    "readers_yay": "sounds/readers_yay.wav"
};

The key of lib.XXX.assets is the name.
It would have some problem if there is duplicated name in different folder.
(For example images/a1.png with /a1.png)

It may be better if the key is the fullpath like images/a1.png;