Force-refresh if data is stale but not expired

[dimo414]

Callers may want to --force refresh only if the cache isn't "fresh" (for some definition of fresh that's less than the TTL) - essentially the opposite of --stale. One such use case is raised in #56, where we only want to --force if the previous non-forced call itself refreshed the cache.

This use case could potentially instead be solved by implementing #47 and letting callers decide when/how they want to trigger additional --warm/--force calls.