Multiple registry support (re: #1401)

[cianclarke]

This is my attempt at #1401, allowing whitespace separated registries to be specified in NPM Client. Still to be done from the numbered list in #1401 is 3), 5), 6), 7) - I'm not sure what 4) means (~/.npm/ is cache folder, right? So should it support caching from both registries?)

This pull request I think solves the main issue I've been having, which is there's no way to have a private instance of the registry which just contains private dependencies and doesn't replicate the full registry.npmjs.org. This allows there to be a 'fallback registry'

Review, comments, etc welcome!

[isaacs]

Remove this, please.

[isaacs]

Before a pull request to npm can be accepted, you should first update https://github.com/isaacs/npmconf and https://github.com/isaacs/npm-registry-client. The changes to npm itself should be virtually nothing.

Closing for now. Please do pursue this in those other repos, though.

[domenic]

Oooh, this is exciting. /cc @indexzero

[indexzero]

+1 hopefully this lands in the other repos @isaacs talked about.

[cianclarke]

Sorry guys - I won't be progressing this further for the time being. Without the further info discussed in #1401 I'm just stabbing in the dark.
-I'm still wondering if there's merit in NPM having multiple instances of an npm-registry-client, each with their own auth, associated couch token, rather than having npm-registry-client look after it's own array of registries, but can be implemented either way..
-Agree npmconf should be updated to have a type for registry which supports multiple, but had difficulty when I went down this avenue..

[isaacs]

@piscisaureus is working on this, a little bird told me.