Adds select/unselect all toggle

Closes #726 

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![image](https://cloud.githubusercontent.com/assets/302258/3961831/ebcf9630-275c-11e4-9186-445b5b1546c2.png)
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![image](https://cloud.githubusercontent.com/assets/302258/3961841/1b3c1e7a-275d-11e4-8f7b-7f1754da7649.png)