add CalculatorSchema

Signed-off-by: n-fukidome <n-fukidome@nekojarashi.com>
exports calculator class

Signed-off-by: n-fukidome <n-fukidome@nekojarashi.com>
repair default setting in calculator

Signed-off-by: n-fukidome <n-fukidome@nekojarashi.com>
Merge pull request #20 from neko2014fresh/add_Calculator_model

Add calculator model