Maybe cherry-pick:

Maybe cherry-pick:
- renamed product -> generic_product
- renamed category -> product_category
- added validators for both product/category i18n keys as direct titles are not
  localizable
- added product manufacturer with is a connection to basic_data entity
- general controller may have reusable methods like allFoos() or
  isFooI18nKeyAdded(), by exposing them in corresponding interface, they can be
  accessed by the administrative bean to check if entity Foo is really not
  there.
- code convention applied: in comparison, first value then variable

Signed-off-by: Roland Häder <roland@mxchange.org>