SEBA-401: Reformat and expand onos-service xproto

Change-Id: If4ff4081d192c02426678c82d00d47367f69ef81
diff --git a/xos/synchronizer/models/models.py b/xos/synchronizer/models/models.py
index 9c01b5b..e4e1948 100644
--- a/xos/synchronizer/models/models.py
+++ b/xos/synchronizer/models/models.py
@@ -24,7 +24,7 @@
     def save(self, *args, **kwargs):
 
         if self.url and not self.version:
-            raise XOSValidationError("If you specify and url, you also need to specify a version. ONOSApp:  %s" % self.name)
+            raise XOSValidationError("If you specify a url, you also need to specify a version. ONOSApp:  %s" % self.name)
 
         super(ONOSApp, self).save(*args, **kwargs)