- Add median service times to cachemgr 'info' page.

- Add median service times to cachemgr 'info' page.
- Fixed DNS service time calculation -- the start time was set as
  the *dispatch* time, not the *request* time, so it only measured
  how long the dnsserver took to process, and did not account for
  queueing delays.
- Fixed ICP svc time calculation -- start time was set way too
  early, before DNS lookups!