Updated from original MarkItUp repository

The original repository contains an update for jQuery 1.9+-compatibility and some style changes. I've integrated these changes here, so the bundle is compatible with recent jQuery versions.

This is especially relevant when you're not using the SonatajQueryBundle in your project, but instead have your own jQuery which is newer than version 1.8.

I also updated the SonatajQueryBundle to use the newer jQuery, for which I'll be creating a separate pull request.