Wrap text in notes box if longer than code in diff

* Fixes branch name overflow
* Text and inline `code` wraps in comments
* `code` blocks scroll horizontally

![Screen_Shot_2016-04-11_at_4.59.15_PM](/uploads/39eee7d35ea79d1a3944aa6281b72121/Screen_Shot_2016-04-11_at_4.59.15_PM.png)

See merge request !3626