* Add new method "names" that parses response from Room#get_all_room
* Reame Result#room_list → Result#parse_room_name
* Rename Message#get_messages → Message#get_history
* Add new method #histroy
Rename Result#parse_room_name → Result#room_names
* Return "Result" object in #history
* Add singleton method "Searcher.search" because of simplification of interface
* Fix spec
* Add "Command#run" method but it is experimental