Schema.org markup

These changes adds few metatags so blog became correctly marked up by [Scheme.org](https://support.google.com/webmasters/answer/1211158). It's good for search engines and for any robots, who wish to use that markup to parse data from web.
You can check sample the result [here](http://www.google.com/webmasters/tools/richsnippets?q=https%3A%2F%2Fterrty.net "Google Structured Data Testing Tool") - any octopress blog with default theme will look like that, changes already commited to [octostrap3 theme](https://github.com/kAworu/octostrap3/pull/26 "Schema.org markup by paskal · Pull Request #26 · kAworu/octostrap3").