CBLT-198:  fix up dpkg --install command

Change-Id: I94b4ffccc005fb80d2db8d452ad102e4873b675c
Reviewed-on: http://review.couchbase.org/34158
Reviewed-by: Philip Labee <philip@couchbase.com>
Tested-by: Philip Labee <philip@couchbase.com>