Show number of failed tests in job view

We've been using a different plugin to display our build wall, since it also shows the number of failed tests -- a metric we find useful on the wall.  This change makes the necessary modifications to the build monitor plugin to allow it to show the number of failed tests, as shown in the screenshot below.

![image](https://f.cloud.github.com/assets/809128/1528897/94d56be4-4c1e-11e3-849e-4ffafc5e26ad.png)