doc: build partial html content as well as full-baked pages

The better to docs.npmjs.com for great good
fs-write-stream-atomic@1.0.2

Now works with streams1 fs.WriteStreams.
convert lib/utils/tar.js to use atomic streams
work around nock's use of setImmediate for 0.8
npm-registry-couchapp tests don't work with 0.8

oh well