Added user permissions, delete user

src/backend/models/user_permission.js

@@ -0,0 +1,30 @@
+// Objection Docs:
+// http://vincit.github.io/objection.js/
+
+'use strict';
+
+const db    = require('../db');
+const Model = require('objection').Model;
+
+Model.knex(db);
+
+class UserPermission extends Model {
+    $beforeInsert () {
+        this.created_on  = Model.raw('NOW()');
+        this.modified_on = Model.raw('NOW()');
+    }
+
+    $beforeUpdate () {
+        this.modified_on = Model.raw('NOW()');
+    }
+
+    static get name () {
+        return 'UserPermission';
+    }
+
+    static get tableName () {
+        return 'user_permission';
+    }
+}
+
+module.exports = UserPermission;