[HOTFIX] Update start-slave.sh

wihtout this change the below error happens when I execute sbin/start-all.sh

localhost: /spark-1.3/sbin/start-slave.sh: line 32: unexpected EOF while looking for matching `"'
localhost: /spark-1.3/sbin/start-slave.sh: line 33: syntax error: unexpected end of file

my operating system is Linux Mint 17.1 Rebecca

Author: Jose Manuel Gomez <jmgomez@stratio.com>

Closes #5262 from josegom/patch-2 and squashes the following commits:

453af8b [Jose Manuel Gomez] Update start-slave.sh
2c456bd [Jose Manuel Gomez] Update start-slave.sh