螢幕鎖(Screen Lock)開啟/關閉

預設是開啟的，要關閉有兩個地方要改：

1. frameworks\policies\base\phone\com\android\internal\policy\impl\KeyguardViewMediator.java

  private boolean mExternallyEnabled = true;
  //set to false if you want disable Screen Lock

2. frameworks/base/packages/SettingsProvider/res/values/defaults.xml

 60000
 // set to -1 if you want disable Screen Lock

兩個都要設定才ok~