replace isotope (100KB) with salvattore (5KB) for feed layout (bug 1092331)

- Salvattore is like a CSS-driven version of Masonry/Isotope. Much leaner at 5KB unmin.
- I had to fork someone's fork of Salvattore that has balanced-height column support and I registered it to Bower as salvattore-moox.

![screen shot 2014-11-10 at 2 39 57 pm](https://cloud.githubusercontent.com/assets/674727/4985169/847bf216-692a-11e4-8fa8-8d3a6902ee1b.png)
![screen shot 2014-11-12 at 7 18 41 am](https://cloud.githubusercontent.com/assets/674727/5012614/59eb6168-6a3c-11e4-8ccb-2bfd62629999.png)
![screen shot 2014-11-12 at 7 18 37 am](https://cloud.githubusercontent.com/assets/674727/5012589/3a3a6a6c-6a3c-11e4-9054-fc6393b810ab.png)



![screen shot 2014-11-12 at 7 17 48 am](https://cloud.githubusercontent.com/assets/674727/5012595/40f1fdb6-6a3c-11e4-8c14-1f61d5b0c392.png)
![screen shot 2014-11-12 at 7 17 59 am](https://cloud.githubusercontent.com/assets/674727/5012598/4270aff2-6a3c-11e4-833a-6863913890a0.png)

why is `require` required? I don't see where it's used.