[MERGE THIRD] Use smartdown version with markdown public API

Update smartdown version with the changes to the api - returning markdown instead of html.

We may want to hold off merging this and bump to 0.11.2 instead as that version has a couple of bug fixes (although I do not think they are manifested anywhere in smart-answers), we would need to create a separate version bump commit anyway)
Maybe i'm missing a trick here, but why is this referencing `smartdown_question` in 2 ways? Why not just
```
markdown_to_html(@smartdown_question.body)
```
where `markdown_to_html` can handle a nil value?