Update layout of Items Curation page

Closes #551 

[x] Remove "Save this search" button from Items Curation page.
[x] Change columns to give more space for title, less space for thumbnail.
[x] Truncate title.
[x] Center Public/Private checkbox toggle column.

![item-admin](https://f.cloud.github.com/assets/96776/2467515/35be1524-afc0-11e3-9ba8-b48b8e32d6a6.png)