[SPARK-4920][UI]:current spark version in UI is not striking.

It is not convenient to see the Spark version. We can keep the same style with Spark website.

![spark_version](https://cloud.githubusercontent.com/assets/7402327/5527025/1c8c721c-8a35-11e4-8d6a-2734f3c6bdf8.jpg)

Author: genmao.ygm <genmao.ygm@alibaba-inc.com>

Closes #3763 from uncleGen/master-clean-141222 and squashes the following commits:

0dcb9a9 [genmao.ygm] [SPARK-4920][UI]:current spark version in UI is not striking.

(cherry picked from commit de9d7d2b5b6d80963505571700e83779fd98f850)
Signed-off-by: Andrew Or <andrew@databricks.com>