settings: Privacy Guard support

 * Add toggle to InstalledAppDetails to enable/disable privacy guard flag on
   a per-application basis.
 * Add toggle to enable privacy guard by default for applications.

Change-Id: If03aa5319c520b6c4a78887f0f46ef1443ddaa83

Conflicts:
	AndroidManifest.xml
	res/values/strings.xml
	src/com/android/settings/SecuritySettings.java