CORS Support by default

[igneel64]

Feature request

(This came from my use of the snapstub package)
Allowing CORS support.
Currently trying to mock some API calls in another localhost instance, the user is faced with CORS issues if the user-agent requires an OPTIONS request.
The handlings that exists currently does not seem to prevent this case:
See

stubborn-server/server/app.js

Lines 15 to 19 in c11f3d4

	app.use(function(req, res, next) {
	res.header('Access-Control-Allow-Origin', '*');
	res.header('Access-Control-Allow-Headers', 'Origin, X-Requested-With, Content-Type, Accept');
	next();
	});

Steps to Reproduce the Problem

1. Start a local application on a different port than the server.
2. Request a resource that would require an OPTIONS request.
3. CORS issue occurs
   Tested in latest Google Chrome

Resolution

By only the addition of the cors middleware, the server is able to handle the OPTIONS request correctly and then move on and allow us to use this package as expected.

If the maintainers think this is a valid request, I can create a PR as soon as possible

[ruyadorno]

Sure thing 👍 I think it does make sense and a PR would be welcome 😄 it would be nice to also have some tests to make sure it doesn't break again in the future 😊 Thanks!