Fix SPARK-1609:  Executor fails to start when Command.extraJavaOptions contains multiple Java options

Author: witgo <witgo@qq.com>

Closes #547 from witgo/SPARK-1609 and squashes the following commits:

deb6a4c [witgo] review commit
91da0bb [witgo] Merge branch 'master' of https://github.com/apache/spark into SPARK-1609
0640852 [witgo] review commit
8f90b22 [witgo] Merge branch 'master' of https://github.com/apache/spark into SPARK-1609
bcf36cb [witgo] Merge branch 'master' of https://github.com/apache/spark into SPARK-1609
1185605 [witgo] fix extraJavaOptions split
f7c0ab7 [witgo] bugfix
86fc4bb [witgo] bugfix
8a265b7 [witgo] Fix SPARK-1609: Executor fails to start when use spark-submit