Add noproxy configuration.

[vvision]

Hello,

Proxy configuration seems to have moved from npm to npm-registry-client, so noproxy configuration should too.

When fetching, check if the url requested must use a proxy (if present) or not.
This allows package installation from lan without having to change/disable the proxy parameter each time.

Previous discussion about noproxy: npm/npm#2873

### noproxy

* Default: `NO_PROXY` or `no_proxy` environment variable, or ""
* Type: String

This variable should contain a comma-separated list of domain extensions proxy should not be used for. For instance, if the value of no_proxy is `.mit.edu', proxy will not be used to retrieve packages from MIT. 

[othiym23]

Hi! I'm leaving this here as a placeholder for the changes described in npm/npm#2873, but this won't be landing as-is. I'll have my eye on it, though.

[othiym23]

Closing this because it's handled elsewhere (i.e. by request). Thanks for putting this together and drawing our attention to this issue, though!