Added authGuard function and its implementations

Also refactored small code mistakes.

api/routes/middleware/authGuard.js

@@ -0,0 +1,23 @@
+// Repository
+const UserRepository = require('../../repositories/user-repository');
+const Users = new UserRepository();
+
+// AUTHGUARD
+const authGuard = (permissions) => {
+    return async (req, res, next) => {
+
+        // Get token from headers
+        let api_token = req.headers['auracle_key'];
+
+        // Uses repo to validate the associated perms with the token
+        Users.checkAPITokenPerms(api_token, permissions)
+            .then(v => {
+                next();
+            })
+            .catch(err => {
+                res.status(err.code).send(JSON.stringify(err))
+            });
+    }
+}
+
+module.exports = authGuard;