Implement self-service web publishing.

Define your host as a CNAME to the sandstorm server and give it a TXT record containing 'sandstorm-www=<publicId>'. The grain's /var/www directory will then be served as static content for your host.
Add Meteor package wrapping Connect, because otherwise it fails to import in production.

Unfortunately, there's no way to specifically request the version used by Meteor. We'll just have to stay in sync for now.
Add getPublicId() method to HackSessionContext for use by web publishing apps.
Fix bugs.