I have made a game framework based on Evennia which includes a game editor on web. This editor is created on django's admin. Its UI is very simple but it can edit the game world online. It can export the game world to a zip file, and I'll add the method of importing the game world from zip file soon. You can create the game world by editing a group of csv or xls files too. If you are interested in it, you can visit our website.
Our website: www.muddery.org
Source code: github.com/muddery/muddery
Demo game: demo.muddery.org