create nested product service model
create item & calculation method model
calculation_method -> calculation , clear service
include simple_form , change form to simple_form
include ZURB Foundation css framework, which use Sass
website layout
product * < -- > * service
disable some feature
view improve
include mongodb
add factory
Merge branch 'master' of github.com:zerdliu/Aqueducts
Merge pull request #6 from zerdliu/master

redesign model and UI