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.
Accidentally left debugger; in
Remove execsync dependency

This dependency was needed to run closure synchronously, which is no longer needed since we have made the build process async. Related #144
doAll.after

Creates a doAll after function that acts as a thunk for async functions. Does the same thing as doAll, but waits until after it has been called.
Merge branch 'node' into require

Conflicts:
	package.json