an operator knows to_s

git-svn-id: https://dev.finn.de/svn/cockpit/branches/reporting_merge@1232 7926756e-e54e-46e6-9721-ed318f58905e

app/models/cost_query/operator.rb

@@ -225,6 +225,10 @@ class CostQuery::Operator
     self
   end
 
+  def to_s
+    name
+  end
+
   def inspect
     "#<#{self.class.name}:#{name.inspect}>"
   end