Execution example::

  % groonga /tmp/groonga-databases/introduction.db
  status
  # [
  #   [
  #     0, 
  #     1337566253.89858, 
  #     0.000355720520019531
  #   ], 
  #   {
  #     "uptime": 0, 
  #     "max_command_version": 2, 
  #     "n_queries": 0, 
  #     "cache_hit_rate": 0.0, 
  #     "version": "4.0.1", 
  #     "alloc_count": 161, 
  #     "command_version": 1, 
  #     "starttime": 1395806057, 
  #     "default_command_version": 1
  #   }
  # ]
