add HTTP API for smoosh:status()

[janl]

This is only available in remsh at the moment, it’d be nice to get at this with HTTP.

E.g. /_node/_local/_smoosh/status

smoosh:status().
{ok,[{"upgrade_dbs",
      [{active,0},{starting,0},{waiting,[{size,0}]}]},
     {"slack_dbs",[{active,0},{starting,0},{waiting,[{size,0}]}]},
     {"slack_views",
      [{active,0},{starting,0},{waiting,[{size,0}]}]},
     {"upgrade_views",
      [{active,0},{starting,0},{waiting,[{size,0}]}]},
     {"index_cleanup",
      [{active,0},{starting,0},{waiting,[{size,0}]}]},
     {"ratio_views",
      [{active,0},{starting,0},{waiting,[{size,0}]}]},
     {"ratio_dbs",
      [{active,0},{starting,0},{waiting,[{size,0}]}]}]}