fixes #1510 - notification when host finishes building

![build_complete](https://cloud.githubusercontent.com/assets/429763/4964849/4adf1836-6771-11e4-9410-1324a7373212.png)

Yea, this is the title in the e-mail like: <b>FOREMAN</b> BUILD COMPLETE

I was figuring that some of these titles I've used in Katello and Foreman have already been translated and was trying to be efficient, so this should really be `<%= _("<b>FOREMAN</b> BUILD COMPLETE") %>`?