Windows support

These are a few changes to better support Windows.  We may want to add a warning to the documentation that we don't really want to support Windows, but are just including it as is.
I'm OK with this. In fact I think it uncovers some behavior that we might want to change; we also have grunt and grunt CLI in the local npm package requirements list, so I'm not sure how that will play with also having them installed globally. Either way, this is probably a good change since our install docs assume grunt is on the path.