New theme: Clear Blog

Create this theme using ``Clean Blog Layout`` in [startbootstrap.com](http://startbootstrap.com). Features:

 - Using bootstrap 3;
 - Responsible layout;
 - Custom header cover like Medium (Pages and Articles);
 - 5 colorschemes to code blocks;
 - Define various analytics: Google Analytics, Gauge and Piwik;
 - Documentation (in development);