add SiteUpdate model

src/c3nav/site/management/commands/createsiteupdate.py

@@ -0,0 +1,15 @@
+from django.core.management.base import BaseCommand
+
+
+class Command(BaseCommand):
+    help = 'create a site update, asking users to reload the page'
+
+    def handle(self, *args, **options):
+        result = input('Type YES to create a new site update: ')
+
+        if result == 'YES':
+            from c3nav.mapdata.models import SiteUpdate
+            SiteUpdate.objects.create()
+            print('New site update created.')
+        else:
+            print('Aborted.')

src/c3nav/site/migrations/0003_siteupdate.py

@@ -0,0 +1,22 @@
+# -*- coding: utf-8 -*-
+# Generated by Django 1.11.7 on 2017-12-24 00:13
+from __future__ import unicode_literals
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('site', '0002_announcement_tweaks'),
+    ]
+
+    operations = [
+        migrations.CreateModel(
+            name='SiteUpdate',
+            fields=[
+                ('id', models.AutoField(auto_created=True, primary_key=True, serialize=False, verbose_name='ID')),
+                ('created', models.DateTimeField(auto_now_add=True, verbose_name='create')),
+            ],
+        ),
+    ]

src/c3nav/site/models.py

@@ -43,3 +43,10 @@ class Announcement(models.Model):
     def save(self, *args, **kwargs):
         super().save(*args, **kwargs)
         cache.delete('site:announcement')
+
+
+class SiteUpdate(models.Model):
+    """
+    A site update that asks the user to reload the page.
+    """
+    created = models.DateTimeField(auto_now_add=True, verbose_name=_('create'))