Use npm config object over custom.

[joshmanders]

Is there any specific reason that standard exists on the root package.json object and not in the global config object? https://docs.npmjs.com/files/package.json#config

[feross]

Interesting. Didn't know about the "config" property when we added the "standard" option. There's already a popular practice of just adding config options directly to the root of package.json, for example: "browserify" and "browser" are two that I'm aware of.