When @Tagging someone in an item, subscribe them as well

[shamrell (Steve Hamrell)]

HI there, posting my first feature request here. It would be really helpful to have objects wrok so that if i tag someone in an update on an item that i can subscribe them to the item. I know if i assign them to the item it does this, but when working in a cross-functional team this would be really good so that if i need the opinion of someone not assigned the work item they can still be notified as things happen to the item being worked.