Get CORS support working with XHR preflight

[paulmelnikow]

Without this patch, http-server returns 404 on the preflight request (method: 'OPTIONS'). You can see the problem by loading an XHR request in Chrome.

[ralyodio]

I tried your fork and i still get a 404

edit: nevermind, my app was sending Authorization header which was causing it to be rejected

[ralyodio]

+1 for merging this!

[paulmelnikow]

ping @indexzero, can you get this merged?

[indexzero]

@paulmelnikow can you rebase off master?

[paulmelnikow]

done

[indexzero]

@paulmelnikow read a little closer, there is actually a --cors option in the CLI, but in this implementation the corser middleware is added by default. Can you make it respond to the option? Then I'll merge.

Bonus points if you write tests.

[paulmelnikow]

Ah, makes sense. I'll take another pass.

[paulmelnikow]

Updated, now honoring the cors option. Includes a test which fails if you remove cors: true. Moved the cors header config into http-server.js so it works in the test.

[indexzero]

Awesome! Merging. Thanks for writing the tests 💯