Cross-session pathing

[#1]

As we start to look at more customer based interactions, cross-session pathing becomes more and more important for s.props. I would love to see the option to have the ability to have cross-session pathing based on the vistor ID with an expiration setting just like an evar.

[#2]

For what it's worth, this was one of the features demonstrated at Summit in Discover 3. That isn't quite the same as having it in SiteCatalyst, but it's a start.