added "special" and "code" syntax styles (Stepic MD)
added img embeding options

Squashed commit of the following:

commit b6ea2f3e769eabce7bf19438e8b2ccfd429ac070
Author: Artem Suschev <Suschev.Artem@gmail.com>
Date:   Tue Oct 22 20:19:15 2013 +0400

    added img embeding options