Dynalon

Author of MDwiki here. Versioning and editing is indeed intended to be done and handled through git. Pull requests are prefered method for collaboration. Another way is to place the wiki on a Dropbox shared public folder and share the folder with your collaborators. Hosting can be done through Dropbox as well.

Crawling is an issue. But if you google for mdwiki, first result will be the projects website which IS crawled. I think this is undocumented by google, but they do fetch ajax content. But you can not do professional SEO with frontend-only solutions.