Execution example::

  logical_table_remove \
    --logical_table Logs \
    --shard_key timestamp
  # [
  #   [
  #     -2, 
  #     1337566253.89858, 
  #     0.000355720520019531, 
  #     "operation not permitted: <[table][remove] a column that references the table exists: <Bookmarks.log_20160320> -> <Logs_20160320", 
  #     [
  #       [
  #         "Groonga::Sharding::LogicalTableRemoveCommand.remove_table", 
  #         "/home/kou/work/c/groonga.clean/plugins/sharding/logical_table_remove.rb", 
  #         80
  #       ]
  #     ]
  #   ]
  # ]
