Install java7 runtime with logstash root manifest.

Logstash depends on java but the runtime wasn't being installed by
the Logstash manifest. Fix this.

Change-Id: I63f2c9831a9c9eae63f4eebd2493800dd606f8fb
Reviewed-on: https://review.openstack.org/30919
Reviewed-by: Jeremy Stanley <fungi@yuggoth.org>
Approved: Clark Boylan <clark.boylan@gmail.com>
Reviewed-by: Clark Boylan <clark.boylan@gmail.com>
Tested-by: Jenkins