Tidied up login page/navbar.

src/controllers/loginController.js

@@ -29,6 +29,12 @@ module.exports.get = async function(req, res){
     //Check for validation errors
     const validResult = validationResult(req);
 
+    //If this request is coming from someone who's already logged in
+    if(req.session.user != null){
+        //Redirect them to the homepage
+        return res.redirect('/');
+    }
+
     //If there are none
     if(validResult.isEmpty()){
         //Get username from sanatized/validated data