Add libxml-simple-perl for "set smoke test param" task
Change-Id: Ibcf99ab7f5f87969b0a8160553aed09abe4cccbf
Reviewed-on: http://review.couchbase.org/40518
Reviewed-by: Chris Hillery <ceej@couchbase.com>
Tested-by: Chris Hillery <ceej@couchbase.com>