Update NEWS for v2.0.0 RC1
Update NEWS for v2.0.0 RC1

andyflury/opentsdb,ShefronYudy/opentsdb,johann8384/opentsdb,MadDogTechnology/opentsdb,alienth/opentsdb,OpenTSDB/opentsdb,eswdd/opentsdb,ShefronYudy/opentsdb,eswdd/opentsdb,MadDogTechnology/opentsdb,OpenTSDB/opentsdb,andyflury/opentsdb,OpenTSDB/opentsdb,johann8384/opentsdb,MadDogTechnology/opentsdb,alienth/opentsdb