Dropdown menu

![happened](https://cloud.githubusercontent.com/assets/8581347/5195154/6a2e6434-74dd-11e4-947c-dc9c5b0b472e.jpg)

I see a couple components in here that you've required but aren't using. Should remove
ButtonGroup
MenuItem

Also, @ajlende mentioned a while ago that when requiring React we should `require('react/addons')`. I have no clue why.