Redcarpet instead of kramdown as markdown renderer

Vieux Port de Montréal, October 2015 - Oneplus one
Redcarpet is the engine written in C by Github, It’s also known as Github flavored markdown. I’ve been using kramdown since the beginning but apparently redcarpet has some cool features like autolinking.
For example if you put a link in your post without using <url> notation or [url text](url), kramdown does not convert those urls into <a> tags. Instead it renders them as raw text in <p> tag.
Here is my config.yaml:
markdown: redcarpet
kramdown:
input: GFM
hard_wrap: false
redcarpet:
extensions: ["autolink", "fenced_code_blocks"]
Here is the full list of available redcarpet extensions: https://github.com/vmg/redcarpet
Btw fenced codeblocks kicks ass, just put your code like this:
```
foo.bar()
```