Use maruku instead of markdown

[jamesflorentino]

Maruku has more advanced features than markdown. For instance, you cannot make a table of contents, a linkable anchor, etc. (see example: http://gist.io/3141153).

Looks great so far :-)

[idan]

For now, I'm planning on using Github's /markdown API endpoint to render markdown. It gets us GFM and consistent rendering.