Style updates to popup panels.

Closes #167 

#### Metadata Panel
![fq789sz0110-md](https://cloud.githubusercontent.com/assets/96776/4980970/ec4bc6f8-6904-11e4-860e-74eabfaad619.png)

#### Embed Panel
![fq789sz0110-embed](https://cloud.githubusercontent.com/assets/96776/4980968/ec4509ee-6904-11e4-8251-22e43cb095e5.png)

#### Download Panel
![fq789sz0110-dl](https://cloud.githubusercontent.com/assets/96776/4980969/ec4a8770-6904-11e4-85ee-71aeb0fe987f.png)