Based on Jon Hall's feedback, bounce karaf default version to 3.0.8.
This is the default for the latest onosproject docker image on dockerhub.
Keep the karaf version for CiaB manifest on 3.0.5.
Add a manifest-cluster.json to spin up a 3 node ONOS cluster with cord-tester.

Change-Id: Ib5b238fd6e32dd46af37d2dd1db5841c1512e7fa
diff --git a/Dockerfile.onos-builder b/Dockerfile.onos-builder
index 6103ce9..096faa9 100644
--- a/Dockerfile.onos-builder
+++ b/Dockerfile.onos-builder
@@ -12,9 +12,9 @@
 ENV HOME /root
 ENV JAVA_HOME /usr/lib/jvm/java-8-oracle
 ENV ONOS_ROOT /src/onos
-ENV KARAF_VERSION 3.0.5
-ENV KARAF_ROOT /root/onos/apache-karaf-3.0.5
-ENV KARAF_LOG /root/onos/apache-karaf-3.0.5/data/log/karaf.log
+ENV KARAF_VERSION 3.0.8
+ENV KARAF_ROOT /root/onos/apache-karaf-3.0.8
+ENV KARAF_LOG /root/onos/apache-karaf-3.0.8/data/log/karaf.log
 ENV BUILD_NUMBER docker
 ENV PATH $PATH:$KARAF_ROOT/bin
 #Download and Build ONOS