Set default as virtual-machine for template

Set virtual-machine as default virtualization type in service
template. If the field is set to None then the default was not
being set.

Change-Id: I2f7435013a4ecfda24bab62293bd58014ac1ab89
Closes-Bug: #1435222

src/config/svc-monitor/svc_monitor/config_db.py

@@ -375,7 +375,7 @@ def update(self, obj=None):
         self.params = obj.get('service_template_properties')
         if self.params:
             self.virtualization_type = self.params.get(
-                'service_virtualization_type', 'virtual-machine')
+                'service_virtualization_type') or 'virtual-machine'
         self.update_multiple_refs('service_instance', obj)
         self.id_perms = obj['id_perms']
     # end update