Create attic for aging apps

[bdemchak]

We are starting to collect apps that are apparently old and unloved ... meaning they don't have editors that respond and have stopped working (e.g., Semascape).

Rather than kick them out of the store, we should retire them to an Attic where they can still be reached but don't occupy top-of-mind for most store users.

First, we need a policy for what goes into the Attic, and then we need to develop a simple UI for users to rummage.