aegir lint should warn when you have js files that aren’t being linted

[mikeal]

I had been putting all my code in lib/ and didn’t realize this basically opted me out of the linting for all of those files.

It would be nice if the linter printed warnings when you have files that aren’t detected by the linter.

Also, we may want to be more flexible about top level files other than index.js. I typically have a cli.js and potentially a browser.js when I have a separate top level entry point for the browser.