Add RWS::Books::Book for supporting Books search API
Bump up the version to 0.2.4
Replace fixture JSON file for testing books API
Define spec for RWS::Books::CD
Ignore .ruby-version
RWS::Books::CD supports BooksCD API
RWS::Books::DVD supports Books DVD/Blu-ray Search API
Rearrange require statements
Target of travis CI includes all branches
Support RWS::Books::ForeginBook API
Support RWS::Books::Magazine API
RWS::Books::Game supports Rakuten Books Game API
Fix typos
RWS::Books::Software supports Rakuten Books Software API
Define RWS::Books::Genre class to support Books Genre API
Refactor: User intance var to store genre info instead of class var
Books::Genre.new asks API only at the first time to initialize a givne id
RWS::Books::Genre.root is alias of new with the root genre id '000'
RWS::Books::Genre#children returns Genre objects under the genre
Refactor RWS::Ichiba::Genre#children in readability