tidies to sudo

`sudo -s` caused an error on centos 6.3, and looking at the man page it's right (not sure why it ever worked), and looking at the javadoc it is clear the somewhat more sensible `-S` was meant

i've switched to `-S` though i'm tempted to ditch both in favour of `-n` which is also specified, and which says not to prompt for a password.  unless there are environments where `-n` isn't available?