Vaguely working test for Age header behaviour
Vaguely working test for Age header behaviour

This test has two main issues:

* When the IP address for the Edge changes (when the A record times out),
  the Age header is reset -- the value is not preserved acrosss Fastly locations.

* The Age header is being reset to 0 by Fastly, so our assumptions about the behaviour
  (that this should be additive) are incorrect.

mikepea/cdn-acceptance-tests,mikepea/cdn-acceptance-tests,alphagov/cdn-acceptance-tests,mikepea/cdn-acceptance-tests,alphagov/cdn-acceptance-tests,alphagov/cdn-acceptance-tests,mikepea/cdn-acceptance-tests,alphagov/cdn-acceptance-tests