Fix publish bar tag scrolling div

Continues on from #4128

- Increases height of tags div and adds `overflow-y: hidden;` to its parent

In browsers with always-visible scrollbars, the tags were a bit screwed up. This fixes that.

![ss 2014-09-24 at 02 39 08](https://cloud.githubusercontent.com/assets/390392/4389499/aeeb4c72-43f5-11e4-992b-80a1405c0ee3.png)