Add TestCacheCacheControlNoStore

Test no-store in addition to no-cache. The RFC states that this should never
be cached. However our behaviour on Varnish and Fastly is currently the same
as no-cache, in that it will be cached.
Adjust mock for Cache-Control: no-(store|cache)

Configure Varnish not to cache responses with `Cache-Control: no-store` or
`Cache-Control: no-cache` headers.

This is the same as we've applied to our internal cache at origin:
http://github.gds/gds/puppet/commit/8c5c1876b3860fad386357bfdc0b94d12c03c878

Technically no-cache should be handled more delicately. In that it should
revalidate content and consider listed field names.
Move CC no-(store|cache) from Cache to NoCache

The mocks have been adjusted in the previous commit. These tests now pass on
CloudFlare by default. We'll need to adjust our Fastly configs, which I
think is probably the right direction to go.
Merge pull request #83 from alphagov/cc_no_cache_no_store

[#76066342] Move CC no-(store|cache) from Cache to NoCache