android device admin: password for un-installation

http://developer.android.com/reference/android/app/admin/DeviceAdminReceiver.html
http://stackoverflow.com/questions/24995553/android-require-password-when-uninstall-app
https://github.com/CharonChui/AndroidNote/blob/master/Android%E5%9F%BA%E7%A1%80/%E8%B6%85%E7%BA%A7%E7%AE%A1%E7%90%86%E5%91%98(DevicePoliceManager).md

That's why device can be locked by "Android Device Manager" with new password...