修改系统锁屏policy

http://www.eoeandroid.com/thread-93269-1-1.html

http://wenku.baidu.com/view/b2f5d7ef4afe04a1b071deb9.html

http://blog.youkuaiyun.com/qinjuning/article/details/7505703

图片等资源在

/源码/frameworks/base/core/res/res/drawable-hdpi