Allow options under "steal"

[matthewp]

Keep "system" for backwards compat, but allow "steal" to be the package.json object. No difference otherwise.

[mjstahl]

Per conversation with @matthewp today.

Add a helper function to npm-utils.js. Something like:

utils.config = (pkg) => return pkg.steal || pkg.system;

Then update the all the code to use the util function as opposed to accessing the pkg.system property directly.

Also update all of the steal docs, and READMEs.

[pYr0x]

@mjstahl is there a working branch i can also worked on?

[mjstahl]

@pYr0x No sir there is not, so if you wanna go ahead and start one. Be my guest. Haven't had a chance to get to it yet.

[matthewp]

Closed by #184