closesTryGhost/Team#2094
This value can be used for non-crucial data with a `public` option. For example: `public, max-age=1, stale-while-revalidate=9`.
The idea behind this option is that the browser would cache the value for the number of seconds in `max-age` and would use it for the number of seconds in `stale-while-revalidate` until it gets a "validated response" from the server. The behaviour should be almost unnoticeable for the end user but would make a big difference in the amount of requests to server.
- because of how the npm scripts were set up, we were running the full
Admin integration tests during the unit tests phase of CI
- this commit renames the majority of `test` to `test:unit` in the
package.json files, and aliases `test` to `test:unit`
- special packages like Admin have no-op'd `test:unit` scripts so we
don't end up running its tests
refs https://github.com/TryGhost/Toolbox/issues/363
- this middleware is standalone and I suspect we're going to be touching
it further when we work on Ghost's caching in the near future
