version 4: Retrieve GPG keys asynchronously.

[Daniel Kahn Gillmor]

In id:87blw1rldy.fsf at tethera.net, bremner identified two of my edits
breaking dme's series that permits asynchronous retrieval of OpenPGP
keys.

This is a revision of that series that should apply to the current
master, taking into account my earlier fixes.

dme, if you could review i would appreciate it.  I think i've done
what you would have done, but as usual my elisp skills are weaker than
yours, so i welcome your feedback.  The test suite passes for me at
least :)

Sorry for contributing to the collision earlier!

      --dkg