RSS フィードを取得するメソッドを分離
SocialData::LivedoorReader を実装
Merge branch 'feature/livedoor' into develop
SocialData::LinkedIn を実装
Merge branch 'feature/linkedin' into develop
SocialData::Buzzurl を実装
Merge branch 'feature/buzzurl' into develop
テストを更新
SocialData::SharedCount を実装