Insert knitr Markdown chunk with snippet

[albertostefanelli]

Thanks for the support for this amazing package. I inserted a snippet to add a chunk with a shortcut such as

```{r }```

The code is adapted from sublime-knitr. The shortcut is now super+alt+c

[randy3k]

Thanks for the PR. Though I am not a big fan of defining for shortcuts. Let me think of a better way to support it.

[albertostefanelli]

closed since i've messed up with the branches