core: Remove the initialize method for cookies on customer

Comable::Customer.new(cookies) => Comable::Customer.new.with_cookies(cookies)
rspec: Refactor the cookies stub to common
core: Remove the preorder method on customer

Comable::Customer#preorder => Comable::Order#invalid?
core: Remove the complete? and incomplete? method on order

Comable::Customer#complete? => Comable::Customer#completed?
core: Remove the reset cart method on customer

Comable::Customer#reset_cart => Comable::Customer#reload
Remove family and first name columns on order
Remove family and first name columns on customer
Revert "rubocop: Exclude the files temporarily"

This reverts commit d76c2701edd43d41961444146ca51886686ce9c9.
Merge pull request #48 from hyoshida/remove-deprecated-methods-and-columns

Remove deprecated methods and columns