I've used prose [0] with a few clients. Its just a web interface for messing with Jekyll, hosted on GitHub. So you might have to upload the Jekyll site to GitHub once, but after that you can edit it as you like.

It also adds some configuration that you can add to Jekyll's config, letting you decide how each menu in the admin console should appear. [1]

[0] http://prose.io/

[1] https://github.com/shakna-israel/haddonRevamp/blob/gh-pages/...