Replace 0.0.0.0 with localhost on open

[mstijak]

Summary
It's common to set host: '0.0.0.0' to enable access to the development server from the network, but that doesn't play well if open: true is set.
Chrome displays an error instead of the application.

The fix is simple. Replace 0.0.0.0 with localhost before passing the URL to the browser.

Does this PR introduce a breaking change?
No

Other information
See http://superuser.com/questions/846721/chrome-wont-access-http-0-0-0-04200.

[jsf-clabot]

All committers have signed the CLA.

[korotkin]

npm start -- --host 0.0.0.0

[mstijak]

@korotkin
This PR fixes the probem if you use --open and --host 0.0.0.0. 0.0.0.0 is not a valid IP address and Chrome refuses to open it.

npm start --host 0.0.0.0 --open

[SpaceK33z]

I merged #746, so it's now possible to add --public localhost and it will use the correct URL to open the site. It's a bit more config, but you can't always assume that it works correctly for localhost.