Allow cordvtn to work without XOS for now

Change-Id: I6c9bb199879ecdb0b68538475135cac424136ab3

@@ -193,7 +193,6 @@ public class CordVtnConfig extends Config<ApplicationId> {
     public XosAccess xosAccess() {
         JsonNode jsonNode = object.get(XOS);
         if (jsonNode == null) {
-            log.error("Failed to get XOS configurations");
             return null;
         }
 

@@ -779,7 +779,10 @@ public class CordVtn extends AbstractProvider implements CordVtnService, HostPro
      * @param xosAccess xos access
      */
     private void setXosAccess(XosAccess xosAccess) {
-        checkNotNull(xosAccess, "XOS access is not configured");
+        if (xosAccess == null) {
+            log.warn("XOS access is not configured");
+            return;
+        }
 
         log.debug("Set XOS access with Endpoint: {} User: {} Passwd: {}",
                   xosAccess.endpoint(),