Update core.js with test for handlerError
Add core-handleError.js for testing fall-through
Add public/404.html for fall-through behavior
Update express.js with test for handleError
Add express-handleError.js for testing fall-through
Update union.js with test for handleError
Add union-handleError.js for testing fall-through
Add new handleError option default for fall-through
Fix #75 when using handlerError with a 404.html in root dir
Update README with opts.handleError documentation
[dist] v0.4.9