Incorporate WebmentionDressing

There's an "iframe ready" [gist](https://gist.github.com/thedod/78b14341e39ca0d09131) now ([demo](http://bl.ocks.org/thedod/78b14341e39ca0d09131)), and it's really easy to theme (I think).
tl;dr you just put this in an iframe and use your path as the URL hash (`#IndieAuth`, `#2014/Online`, etc.)
If you're game (just nod), I can fork an alternative theme (maybe without bootstrap) and we can have a theme selection dropdown and a "fork and propose your own theme" link. Could be fun.

Start by reviewing the linked WebmentionDressing gist and demo to understand the iframe and URL-hash approach. Done would mean incorporating that presentation into the wiki and deciding whether to include the proposed theme selector and link for creating alternate themes.

Written by the indexing model from the issue text.