Add no-unused-vars args: after-used config

[dihar]

Now we can's use snippets like this

[1, 2, 3, 4].filter(function(el, i){
  return i % 2;
});

without lint error, and we must disable eslint or do this hack

[1, 2, 3, 4].filter(function(_el, i){
  return i % 2;
});

I propose add option of no-unused-vars``args: after-used config. I will resolve the problem.