specify a remote w/ dependencies

[jonathanong]

migrated from #42

most obvious would be something like github.com/component/emitter. problem is that this might get ugly with super custom remotes, but we'll see.

[jonathanong]

so.... we should support:

• whatever browsers support via import statements and stuff
• <remote name>:<user>/<repo>
• <hostname>/<user>/<repo>
• <user>/<repo. - what we have right now, but it checks every single remote

what do you think? @visionmedia

[tj]

I'm leaning towards domains just because we could have default behaviours at some point, like check <link rel= tags for tarballs etc. That's way too fancy for now but it would be a shame to rule it out. I do like remote:user/repo as well but it only saves a few chars I guess haha.

Checking a list of remotes is handy for a lot of things but I guess it could get pretty confusing too.