res/greeter::fixed greeter and lock has not sky animation of background

resolve:
    use setTimeout to execute init() function

reason:
    when document.body.onload=init ,the canvas in three.js perhaps will not ready.

tower:https://tower.im/members/6440fe0bf4f944baa5c5e99137a521e8/?me=1

Change-Id: If70f8f9a91b3b57a3341242dbe2d77e67be81e3a