Add hint for disabled social auth service

Author: gocreating

src/server/controllers/socialAuth.js

@@ -1,6 +1,12 @@
 import passport from 'passport';
 
 export default {
+  setupError: (req, res) => {
+    res.send(
+      'Please setup and turn on `passportStrategy.<social provider>` ' +
+      'of config file `configs/project/server.js`'
+    );
+  },
   initFacebook: (req, res, next) => (
     passport.authenticate('facebook', {
       scope: ['public_profile', 'email'],

src/server/routes/socialAuth.js

@@ -11,6 +11,8 @@ export default ({ app }) => {
       passportAuth('facebook'),
       userController.socialLogin
     );
+  } else {
+    app.get('/auth/facebook', socialAuthController.setupError);
   }
   // linkedin
   if (configs.passportStrategy.linkedin) {
@@ -19,5 +21,7 @@ export default ({ app }) => {
       passportAuth('linkedin'),
       userController.socialLogin
     );
+  } else {
+    app.get('/auth/linkedin', socialAuthController.setupError);
   }
 };