[SPARK-4870] Add spark version to driver log

Author: Zhang, Liye <liye.zhang@intel.com>

Closes #3717 from liyezhang556520/version2Log and squashes the following commits:

ccd30d7 [Zhang, Liye] delete log in sparkConf
330f70c [Zhang, Liye] move the log from SaprkConf to SparkContext
96dc115 [Zhang, Liye] remove curly brace
e833330 [Zhang, Liye] add spark version to driver log