Shop owner groups and sub owners

[BrendonButler]

The shop owner should also be able to be set to a group, such as "operators." Then permissions such as (shops.update.default.) could be used to permit updating items in the shop.

Optional co-owners should be allowed as well whether they be a group or individual users. It may make sense to have a flag to enable or disable co-owners from having full access to the shop (such as using the delete command)