Updated charting tooltips to include header and updated labels.

Education:
![edu](https://cloud.githubusercontent.com/assets/5265058/4943126/a5ef7e4a-65f1-11e4-8f05-66d187d36788.png)

Gender:
![gender](https://cloud.githubusercontent.com/assets/5265058/4943127/a5f212cc-65f1-11e4-8f8f-943cba8fb54a.png)

Age:
![age](https://cloud.githubusercontent.com/assets/5265058/4943128/a5f864ce-65f1-11e4-96e2-6bcf06e5b142.png)

@rocha @clintonb @lamagnifica @marcotuts @shnayder 
I favor replacing "% of students" with "Percentage". @shnayder , @marcotuts ?