修正dispatcher，使用redis存任务队列，修正submission的post，修改部分settings

oj/celery.py

@@ -0,0 +1,18 @@
+from __future__ import absolute_import, unicode_literals
+import os
+from celery import Celery
+from django.conf import settings
+
+# set the default Django settings module for the 'celery' program.
+os.environ.setdefault('DJANGO_SETTINGS_MODULE', 'oj.settings')
+
+
+app = Celery('oj')
+
+# Using a string here means the worker will not have to
+# pickle the object when using Windows.
+app.config_from_object('django.conf:settings')
+
+# load task modules from all registered Django app configs.
+app.autodiscover_tasks(lambda: settings.INSTALLED_APPS)
+# app.autodiscover_tasks()