crowbar: Avoid uselessly saving a node on re-allocation of IP

If the node already has the info, then no need to save, which is
expensive.

(cherry picked from commit 2013a47)
(cherry picked from commit 85cf951)

crowbar_framework/app/models/network_service.rb

@@ -122,8 +122,10 @@ def allocate_ip_by_type(bc_instance, network, range, object, type, suggestion =
 
     if type == :node
       # Save the information.
-      node.crowbar["crowbar"]["network"][network] = net_info
-      node.save
+      if node.crowbar["crowbar"]["network"][network] != net_info
+        node.crowbar["crowbar"]["network"][network] = net_info
+        node.save
+      end
     end
 
     @logger.info("Network allocate ip for #{type}: Assigned: #{name} #{network} #{range} #{net_info["address"]}")