Tidy up the SSH call to avoid injection attacks in storwize_svc

Let the command and arguments form up a list and avoid the extra arguments
attackers inserted to the command string

fix bug 1192971

Change-Id: I57b3fe60e64d9d0dc1ea9a18442c877be2ceece3
Merge "Tidy up the SSH call to avoid injection attacks in storwize_svc"