Port the build pipeline and test harness to ES. Fix bug 1030309.

Yet to come: request-time dir listing rendering. Right now, you can't see folder listings, but files are fine.
I've got a sketch sketched. It might gain us a little RAM (and cache hit ratio), but my guess is only a little. We still have to concretize refs and regions eventually (and at the same time), to sort them. Likewise, `annotations` gets zipped and thus concretized, because the file.html template loops through the lines of the file 3 times at present. So, `links` and various kinds of needles are left as the possible wins. We might get a little boost from not having them concretized in RAM at the same time as refs, regions, etc.