Update node.d.ts, remove lib.d.ts, and use tsd to manage .d.ts files

We don't need to ship lib.d.ts, because it comes bundled with the
typescript compiler and gets loaded by default.

Using tsd makes updating typings files in the future as simple as a
single command.

Also removed the --nolib flag to make tsc load its bundled lib.d.ts.
Actually, in typescript 1.3.0, I think the flag is gone and you're
supposed to use /// <reference no-default-lib="true" /> instead.
Overwrite process.mainModule.filename so tsc can resolve lib.d.ts