Use Github Flavoured Markdown as default markdown renderer

Hello there @tomaz, I've taken the discount library updated it to version 2.1.5a ( which has been the released build since Aug 2012 ) and I've compiled it with the ability to do block quotes.

Interested?

![Screen Shot 2013-03-09 at 13 19 15](https://f.cloud.github.com/assets/49038/239696/6bde3f06-88bd-11e2-8653-351274712564.png)
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https://github.com/siuying/IGAutoCompletionToolbar/blob/master/README.md