Don't cache CC no-store/no-cache

Don't cache responses with these headers. In order to match:

- CloudFlare's default behaviour
- cdn-acceptance-tests mocks:
  alphagov/cdn-acceptance-tests@47585a2
- cache-N.router config:
  https://github.gds/gds/puppet/commit/8c5c1876b3860fad386357bfdc0b94d12c03c878

This should come next to the handling of CC private because we want to do
this after 5xx handling and return() before doing anything. I've opened and
closed the comments to indicate that this isn't part of the macro that we've
copied.

Run against the acceptance test service. Two errors are pre-existing:

    dcarley@ci-slave-4:~/cdn-acceptance-tests$ go test -edgeHost fastly.cdn-acceptance-test.alphagov.co.uk -skipVerifyTLS -skipFailover
    2014/08/07 14:17:26 Confirming that CDN is healthy
    2014/08/07 14:17:26 Started server on port 8080
    2014/08/07 14:17:26 Checking health of origin...
    2014/08/07 14:17:27 origin is up!
    --- FAIL: TestNoCacheHeaderCookie (0.08 seconds)
            helpers.go:360: Incorrect response body. Expected "second response", got "first response"
            helpers.go:360: Incorrect response body. Expected "third response", got "first response"
    --- FAIL: TestNoCacheHeaderCacheControlMaxAge0 (0.02 seconds)
            helpers.go:360: Incorrect response body. Expected "second response", got "first response"
            helpers.go:360: Incorrect response body. Expected "third response", got "first response"
    2014/08/07 14:17:54 Started server on port 33265
    2014/08/07 14:17:54 Started server on port 33265
    2014/08/07 14:17:54 Started server on port 49001
    2014/08/07 14:17:55 Started server on port 46997
    2014/08/07 14:17:55 Started server on port 39178
    FAIL
    exit status 1
    FAIL    _/home/dcarley/cdn-acceptance-tests     28.134s

vcl_templates/www.vcl.erb

@@ -185,6 +185,14 @@ sub vcl_fetch {
     return (pass);
   }
 
+  # << not reproduced by macro
+  # >> custom
+  if (beresp.http.Cache-Control ~ "no-(store|cache)") {
+    return (pass);
+  }
+  # << custom
+  # >> not reproduced by macro
+
   if (beresp.status >= 500 && beresp.status <= 599) {
     set req.http.Fastly-Cachetype = "ERROR";
     set beresp.ttl = 1s;