Fixed display of long descriptions in the build history pane

Broken display:
![jenkins-build-history-broken](https://cloud.githubusercontent.com/assets/3975044/4032317/031591e8-2c6f-11e4-9954-9df147efc84c.png)

Fixed display:
![jenkins-build-history-fixed](https://cloud.githubusercontent.com/assets/3975044/4032318/03198a00-2c6f-11e4-8076-30c2590d64ac.png)