Add fix option to comma-spacing (fixes #4232)

[netei]

I'm not sure how to handle the last cases with comments :

        {
            code: "myfunc(404, true/* bla bla bla */ , 'hello');",
            output: "myfunc(404, true/* bla bla bla */, 'hello');",
            errors: [
                {
                    message: "There should be no space before ','.",
                    type: "Punctuator"
                }
            ]
        },
        {
            code: "myfunc(404, true/* bla bla bla */ /* hi */, 'hello');",
            output: "myfunc(404, true/* bla bla bla *//* hi */, 'hello');",
            errors: [
                {
                    message: "There should be no space before ','.",
                    type: "Punctuator"
                }
            ]
        }

doesn't work, it is removing the comments.

[alberto]

You should add the expected output of those tests to the PR, even if it makes it fail (that's the point of the tests afterall).

[netei]

I've added the failing tests

[nzakas]

Then work to fix the tests :)

[netei]

I finally found a solution. The tests pass now

[nzakas]

Change looks good. Can you please sign our CLA? http://eslint.org/cla

[netei]

Signed

[nzakas]

Thanks!