supported by Hong Kong RGC GRF grant (16205314);partially by the research grants from NSFC, China (81171418, 81371649);WP is partially supported by grants from the Fraunhofer-Bessel Research Award from the Alexander von Humboldt Foundation, Germany;the Newton Fund, British Council, UK;the King Mongkut’s Institute of Technology Ladkrabang, Thailand; the Thailand Research Fund, Thailand;the National Research Council, Thailand