Fix some startup issues now that we use cluster size

- Change max cluster size to size of largest cluster
- Cleanup some reading of params
- Catch when ONOS isn't fully started

Change-Id: I5b2ca791046bd4061d31355276958ead39f8b65c
(cherry picked from commit ace1f317e19fd50924e78e53b566d69db23f5683)
diff --git a/TestON/tests/SAMP/SAMPstartTemplate_3node/SAMPstartTemplate_3node.topo b/TestON/tests/SAMP/SAMPstartTemplate_3node/SAMPstartTemplate_3node.topo
index a5de4a9..612b658 100755
--- a/TestON/tests/SAMP/SAMPstartTemplate_3node/SAMPstartTemplate_3node.topo
+++ b/TestON/tests/SAMP/SAMPstartTemplate_3node/SAMPstartTemplate_3node.topo
@@ -22,7 +22,7 @@
                 <rest_port></rest_port>
                 <prompt></prompt>  # TODO: we technically need a few of these, one per component
                 <onos_home></onos_home>  # defines where onos home is on the target cell machine. Defaults to entry in "home" if empty.
-                <nodes> 3 </nodes>  # number of nodes in the cluster
+                <nodes> 7 </nodes>  # number of nodes in the cluster
             </COMPONENTS>
         </ONOScell>