Don't use storage if the cache-control header includes no-cache

**Note: this has outgrown its context.  It's being split up into different component PRs, and should be rebased/squashed when those are merged.**

I'm a bit confused about the tid generation here -- shouldn't the tid always be deterministic, since it's coming from api.php for a given page/revision?  In other words, if we use `no-cache` and go back out to Parsoid, it seems like the tid shouldn't change.