Update package tree styles

The package views have bothered my designery brain for a while so I'm taking a small attempt to clean it up a bit. Even if its just for my local version.

Before on left after on right:
![screenshot 2014-09-17 15 38 32](https://cloud.githubusercontent.com/assets/51578/4309999/410a8f4a-3ea2-11e4-997d-6e67af1cb1dd.png)

- [x] Added version number to package
- [x] Added active styles to author
- [x] Modified scrollbar to not look as 'awkward' with the rest of the ui surrounding it
- [x] Line breaks added around each package
- [x] Responsive Atom logo (responds to width, with max-width set)


Let me know if you have thoughts.
Probably want to include a `.scrollbars-visible-always` class before these scrollbar selectors so they don't show when the "only show scrollbars when scrolling" Mac OS X setting is enabled.