Allow configure routes in the extension’s options

[NV]

routes.js causes a lot of confusion: #7, #14, #15. As suggested in garbelini/chrome-devtools-autosave-server@04a44fd373e039415a694bc5fbf62d60b27cf9df, wouldn’t it be simpler to configure routes in the extension’s options? The idea is to move to from

exports.routes = [
     {
        from: /^file:\/\/[^/]*\//,
        to: '/'
    }
]

into an input field near "Resource" and "Post to".

I used to don’t like sending a path to a file other the network due security reasons. It’s not a issue since most people use it locally or inside the closed network.