Add local HTTP redirect cache for RO resources.
Add local HTTP redirect cache for RO resources.

This is a weak attempt to reduce load on and mitigate errors from
redirection services like Purl.org.  What is really needed here is some
greater resilience in the face of certain kinds of HTTP failures.

wf4ever/ro-manager,wf4ever/ro-manager,wf4ever/ro-manager,wf4ever/ro-manager