npm 1.4.7

Bump npm to 1.4.7, and also that url thing that should probably get landed anyway.

Executive summary of npm changes:

* tests are better
* shrinkwrap doesn't crash as much
* shasums don't get borked
* added `--save-prefix` for saving as `~` or `>=` instead of `^`
* don't print the scripts log message to stdout if `--loglevel=silent`

Can I get a LGTM and land this puppy?