quick verification of ZEO clients less than a given age even if the
number of transactions the client hasn't seen exceeds the
invalidation queue size. This is only recommended if the storage
being served  supports effecient iteration from a point near the end
of the transaction history.

Also refactored ZEO/tests/zeoserver and ZEO/runzeo to have the test
server use, and this exercisem, the option-handling code from runzeo.