Fix #526 -- Add a webhook system (#1073)

- [x] Data model
- [x] UI
- [x] Fire hooks
- [x] Unit tests
- [x] Display logs
- [x] API to modify hooks
- [x] Documentation
- [x] More hooks!

src/pretix/api/migrations/0003_webhook_webhookcall_webhookeventlistener.py

@@ -0,0 +1,79 @@
+# Generated by Django 2.1.1 on 2018-11-07 10:46
+
+import django.db.models.deletion
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('pretixbase', '0102_auto_20181017_0024'),
+        ('pretixapi', '0002_auto_20180604_1120'),
+    ]
+
+    operations = [
+        migrations.CreateModel(
+            name='WebHook',
+            fields=[
+                ('id', models.AutoField(auto_created=True, primary_key=True, serialize=False, verbose_name='ID')),
+                ('enabled', models.BooleanField(default=True, verbose_name='Enable webhook')),
+                ('target_url', models.URLField(verbose_name='Target URL')),
+                ('all_events', models.BooleanField(default=False, verbose_name='All events (including newly created ones)')),
+                ('limit_events', models.ManyToManyField(blank=True, to='pretixbase.Event', verbose_name='Limit to events')),
+                ('organizer', models.ForeignKey(on_delete=django.db.models.deletion.CASCADE, to='pretixbase.Organizer')),
+            ],
+        ),
+        migrations.CreateModel(
+            name='WebHookCall',
+            fields=[
+                ('id', models.AutoField(auto_created=True, primary_key=True, serialize=False, verbose_name='ID')),
+                ('datetime', models.DateTimeField(auto_now_add=True)),
+                ('target_url', models.URLField()),
+                ('is_retry', models.BooleanField(default=False)),
+                ('execution_time', models.FloatField(null=True)),
+                ('return_code', models.PositiveIntegerField(default=0)),
+                ('payload', models.TextField()),
+                ('response_body', models.TextField()),
+                ('webhook', models.ForeignKey(on_delete=django.db.models.deletion.CASCADE, to='pretixapi.WebHook')),
+            ],
+        ),
+        migrations.CreateModel(
+            name='WebHookEventListener',
+            fields=[
+                ('id', models.AutoField(auto_created=True, primary_key=True, serialize=False, verbose_name='ID')),
+                ('action_type', models.CharField(max_length=255)),
+                ('webhook', models.ForeignKey(on_delete=django.db.models.deletion.CASCADE, to='pretixapi.WebHook')),
+            ],
+        ),
+        migrations.AddField(
+            model_name='webhookcall',
+            name='success',
+            field=models.BooleanField(default=False),
+        ),
+        migrations.AlterField(
+            model_name='webhook',
+            name='all_events',
+            field=models.BooleanField(default=True, verbose_name='All events (including newly created ones)'),
+        ),
+        migrations.AlterField(
+            model_name='webhook',
+            name='organizer',
+            field=models.ForeignKey(on_delete=django.db.models.deletion.CASCADE, related_name='webhooks', to='pretixbase.Organizer'),
+        ),
+        migrations.AlterField(
+            model_name='webhookcall',
+            name='webhook',
+            field=models.ForeignKey(on_delete=django.db.models.deletion.CASCADE, related_name='calls', to='pretixapi.WebHook'),
+        ),
+        migrations.AlterField(
+            model_name='webhookeventlistener',
+            name='webhook',
+            field=models.ForeignKey(on_delete=django.db.models.deletion.CASCADE, related_name='listeners', to='pretixapi.WebHook'),
+        ),
+        migrations.AddField(
+            model_name='webhookcall',
+            name='action_type',
+            field=models.CharField(default='', max_length=255),
+            preserve_default=False,
+        ),
+    ]