Fix comment conf file - s/space/comma/
Fix comment conf file - s/space/comma/

Commit fixes comment in 'src/opentsdb.conf' which says list of ZK hosts is a
space separated list, but in reality it's a comma separated list.

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