MB-100: fix formatting of graph poster script

Change-Id: Ie2e1b7d3b83e64f2334dd933cbc96d0a4975baed
Reviewed-on: http://review.couchbase.org/25351
Reviewed-by: Pavel Paulau <pavel.paulau@gmail.com>
Tested-by: Pavel Paulau <pavel.paulau@gmail.com>