Added the functionality to choose country per store.
I think and hope to have changed all the needed files and added all the needed changes for this functionality.
I did that because I needed to add only some countries into specific stores.
I merged the changes with the last commit.
This is the link for my fork:
https://nopcommerce.codeplex.com/SourceControl/network/forks/maurointrozzi/PaypalStandardChooseRedirLandingPage
Commit
Warning! I originally created this fork to add the ability to choose the redirect landing page for "PaypalStandard" plugin, and this add-on still exists in the fork.
I hope this can be an useful change.