MB-100: add -e and -x flags to shebangs

Change-Id: Ie4f72821527707334831ba62310be0c536a9c313
Reviewed-on: http://review.couchbase.org/23889
Reviewed-by: Pavel Paulau <pavel.paulau@gmail.com>
Tested-by: Pavel Paulau <pavel.paulau@gmail.com>