Social icons resize to 32px

- [new] social icons are reusable anywhere and are not tied to the social module
- [new] icon size matches the "home" icon in #3109


![share-icons](https://f.cloud.github.com/assets/85783/2162173/42a4375c-94cf-11e3-8971-f20f54519734.gif)

![ ](http://media.giphy.com/media/uSfZr4NskbtbW/giphy.gif)