Adds app name in HTML page titles on job web UI

This adds the app name to HTML page titles on the job web UI and should fix [SPARK-806](https://spark-project.atlassian.net/browse/SPARK-802).
![environment](https://f.cloud.github.com/assets/4754931/800044/7175917a-ed81-11e2-98e7-97f9fb9be907.png)
![spark pages](https://f.cloud.github.com/assets/4754931/800045/7176fb64-ed81-11e2-9af7-22e676936803.png)
![spark storage](https://f.cloud.github.com/assets/4754931/800046/71878cb8-ed81-11e2-919b-999d287b4562.png)