Restores larger icons since FA upgrade (without changing .icon-large)

**BEFORE:**
![tree_fa4_icon_small](https://cloud.githubusercontent.com/assets/352182/2795842/cb4e7b5e-cc00-11e3-8c32-294d663451b6.jpg)

**AFTER:**
![tree_fa4_icon_large](https://cloud.githubusercontent.com/assets/352182/2795850/dd4358f2-cc00-11e3-906f-818b63363a8b.jpg)