Prices for integer currencies

[vkublytskyi]

Magento should correctly handle currencies without subunits, including JPY.

As tasks actual not only for Japanese yen solution should be implemented in magento/magento2-l10n repository (or in magento/magento2).

This epic includs researching and fixing all places in Magento 2 Open Source with incorrect handling of currency subunits and assumption that for currency valid expression superuints/subunits = 100.

[HirokazuNishi]

Development branch is here:
https://github.com/Veriteworks/magento2-l10n/tree/price-for-integer-currencies

Display integer currencies as integer already works, but removing fraction is not perfect...