Add plugin installation docs and rebuild command

src/pretix/base/__init__.py

@@ -18,3 +18,7 @@ class PretixBaseConfig(AppConfig):
 
 
 default_app_config = 'pretix.base.PretixBaseConfig'
+try:
+    import pretix.celery_app as celery # NOQA
+except ImportError:
+    pass

src/pretix/base/management/commands/rebuild.py

@@ -0,0 +1,15 @@
+from django.core.management import call_command
+from django.core.management.base import BaseCommand
+
+from ...signals import periodic_task
+
+
+class Command(BaseCommand):
+    help = "Rebuild static files and language files"
+
+    def handle(self, *args, **options):
+        periodic_task.send(self)
+        call_command('compilemessages', verbosity=1, interactive=False)
+        call_command('compilejsi18n', verbosity=1, interactive=False)
+        call_command('collectstatic', verbosity=1, interactive=False)
+        call_command('compress', verbosity=1, interactive=False)