Beginning of making js compression async
More working on making minifying async
Got the js tests to pass.
Merge branch 'node' into js-async
Merge branch 'node' of github.com:matthewp/steal into js-async

Conflicts:
	build/js/jsminify.js
Steal build is not async

Too many changes to list, but basically everything had to be refactored (especially packages.js) in order to become async. All tests are passing.