Use a glyphicon instead of the unicode character.

Before:
![before](https://cloud.githubusercontent.com/assets/349621/5304665/8f6eb506-7bfd-11e4-9763-7834f395b9e5.png)

After:
![after](https://cloud.githubusercontent.com/assets/349621/5304666/9387baf2-7bfd-11e4-91f1-2f3875ba85b6.png)

/CC @mdo