Updated documentation and dev scripts

Hi @isaacs,

Documentation and dev scripts in npm-www seems to be a bit outdated, I am sending changes required to bring them up to date with the source code.

- added 'registry/error: forbidden' to the list of replicated documents,
otherwise private npm-www does not work (fixes isaacs/npmjs.org#98).
- added elasticsearch configuration to dev/ folder and modified dev/go.js
to start elastichsearch and npm2es (npm to es synchronization).
- Modified README.md to mention elasticsearch as a prerequisite.

I have also extracted replication of design documents into a standalone file, so that you can initialize your Couch DB without replicating data from the public registry.

Could you please review?

Miroslav