Delay in opening, makes a network request

[slikts]

Since the editor is just an iframe, every time it's opened it makes a network request to https://stackedit.io/app, and there's a noticeable delay. The request returns a 304 status, but it takes time anyway and makes for a poor user experience. Ideally the editor should be served locally or at least from service worker cache.

[slikts]

It also requests https://stackedit.io/conf, and in total this seems to delay opening the editor by at least 400ms.