Redirecting to previous page after login(KamandPrompt#105)

Issue KamandPrompt#105
Changes are done in auth.js file of the controls section
Changes are done in order to redirect to previous page after login action

express-back uses sessions to track the previous path the user visits 
res.redirect('back') redirects to URL of the previous page that the express-back gives

Fixes: KamandPrompt#105

controls/auth.js

@@ -2,6 +2,7 @@ var passport = require('passport');
 var user = require('../models/users');
 var submissions = require('../models/submission');
 var moment = require("moment");
+var back = require("express-back");
 
 /**POST: user signup 
  * route: /user/signup
@@ -78,7 +79,7 @@ exports.postLogin = function (req, res) {
 */
 exports.getLogout = function (req, res) {
     req.logout();
-    res.redirect('/');
+    res.redirect('back');
 }
 
 /**Implementing the routing guards */