[Coreshop] possibility to resolve stores to set on products from import (via name)

[dkarlovi]

Q	A
Bug report?	no
Feature request?	yes
BC Break report?	no
RFC?	no
Branch?	master

If you want to import a product and automatically set one or more stores to it from the import, you should be able to. Current StoresInterpreter only accepts config which doesn't allow you to reuse import definitions.

This looks like a Coreshop-specific feature, see #291 which seems relevant.