added config for the tunnel server to the schema

lib/admin/config.js

@@ -174,6 +174,14 @@ var mdnsSchema = {
   }
 };
 
+var tunnelSvrSchema = {
+  type: 'object'
+, properties: {
+    servernames: { type: 'array', items: { type: 'string' }}
+  , secret:      { type: 'string' }
+  }
+};
+
 var ddnsSchema = {
   type: 'object'
 , properties: {
@@ -223,6 +231,7 @@ var mainSchema = {
   , ddns:   ddnsSchema
   , socks5: socks5Schema
   , device: deviceSchema
+  , tunnel_server: tunnelSvrSchema
   }
 , additionalProperties: false
 };