hbal: allow, but warn on, N+1 failed clusters

Based on the node changes, we remove the N+1 check and only show a
warning instead.

src/hbal.hs

@@ -148,8 +148,7 @@ main = do
              (length bad_nodes) (length bad_instances)
 
   when (length bad_nodes > 0) $ do
-         putStrLn "Cluster is not N+1 happy, please fix N+1 first. Exiting."
-         exitWith $ ExitFailure 1
+         putStrLn "Cluster is not N+1 happy, continuing but no guarantee that cluster will end N+1 happy."
 
   when (optShowNodes opts) $
        do