xmlns:app="http://schemas.android.com/apk/res-auto"即可，参考：http://stackoverflow.com/questions/18871005/error-parsing-xml-unbound-prefix-on-library
xmlns:app="http://schemas.android.com/apk/res-auto"即可，参考：http://stackoverflow.com/questions/18871005/error-parsing-xml-unbound-prefix-on-library