Remove unstyled border from iframe

My dashboard has an unwanted border wherever the `iframe` portlet is used.  You can customize the style of the surrounding `div` if you want to add the border back.

#### Before

![before_with_border](https://cloud.githubusercontent.com/assets/90153/3737464/2ca66e76-1737-11e4-8b34-f62417995bd3.png)

#### After

![after_without_border](https://cloud.githubusercontent.com/assets/90153/3737470/36a8f448-1737-11e4-89f9-db57ccf7f668.png)