Update dependencies.

* `commander` to 2.5.0
* `es6-shim` to 0.20.2
* `prfun` to 1.0.1
* `jshint` to 2.5.0 (and jshint added to `npm test`)
* `mocha` to 2.0.1

Change-Id: Ib7839d347ea41e54de22c372f1138749a714ce0f
Be quiet when unzipping; don't create pipes in `P.spawn`.

Both these changes ensure that we don't block for pipe input when
unzipping large bundles.

Change-Id: Id1ff90cd5b3c07d818625650a7a75ed9887660e5