Feature/jschatz1/sidebar features
* Changes sidebar width (290px).
* Makes shortcuts for <kbd>j</kbd> and <kbd>k</kbd> keys for next and previous issues.
![Screen_Shot_2016-02-05_at_3.06.22_PM](/uploads/8590be43dc1b9feffd4f32b4e8cb7790/Screen_Shot_2016-02-05_at_3.06.22_PM.png)
cc/ @dzaporozhets
See merge request !2734