Fixed issue on compute nodes iteration

In this changeset, I fixed the issue with the basic server
consolidation strategy to now loop over all compute nodes
as expected instead of stopping after the first one.

Change-Id: If594f0df41e39dfb0ef8f0fce41822018490c4ec
Closes-bug: #1548874

watcher/tests/decision_engine/model/faker_cluster_and_metrics.py

@@ -70,6 +70,13 @@ class FakerModelCollector(base.BaseClusterDataModelCollector):
         """
         return self.load_model('scenario_3_with_metrics.xml')
 
+    def generate_scenario_4(self):
+        """Simulates a cluster
+
+        With 4 nodes and 6 instances spread on all nodes
+        """
+        return self.load_model('scenario_4_with_metrics.xml')
+
 
 class FakeCeilometerMetrics(object):
     def __init__(self, model):