add es6 exports for the things we use
revert the changes to export default introduced during spec flap a while back.

also support new unspec'ed syntax for module imports:  import * as ident from 'source'

this can be mixed with other import specifiers (including default and named), so you could conceivably end up
with this monstrosity:

  import * as foo, bar, { baz, blip } from 'grab-bag-module';

which would bind foo to the module object, bar to the default export, and blaz/blip to named exports.