Ported to node, closes #1

Am I crazy here?

The registry situation is out of hand. I think that the rewrite everything, wholesale change idea only works when there is a good momentum for it, which we don't have.

I have created here the simplest possible port I could. It will then be possible to port features and code from the node_rewrite branch over time, and importantly, test them out in the real world a little bit at a time.

It allows us to accept PRs for features rather than asking people to jump in to a whole complicated re-architecting.

Next steps, things that could be handled modularly, by any one:
- Support SSL
- Add auth based on the user being a collaborator on the linked repo
- Allow unauthed deletion of a package that is very new and has low usage
- Move to CouchDB

@satazor @sindresorhus @paulirish @svnlto

PS. I imagine that pushing this to Heroku would "just work" - I'm using their environment variable for the database, and I tested this against the live database too. Any potential issues?