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/src/test/setup/manifest-cord.json b/src/test/setup/manifest-cord.json
index a83be39..d4222a6 100644
--- a/src/test/setup/manifest-cord.json
+++ b/src/test/setup/manifest-cord.json
@@ -9,5 +9,6 @@
     "synchronizer" : "vtn",
     "docker_network" : "onoscord_default",
     "log_level" : "INFO",
-    "jvm_heap_size" : "1G"
+    "jvm_heap_size" : "1G",
+    "karaf_version" : "3.0.5"
 }