Merge branch 'dev-sxw' into virusdefender-dev

* dev-sxw:
  实现了比赛提交列表里封榜的行为，封榜以后只显示缓存里的提交数据和封榜后自己的提交，封榜以后rank不再刷新（rank里还不会显示自己封榜以后的提交。。。这好像不对呀）
  增加比赛提交页面封榜行为
  修改函数名称
  为User   problems_status 添加默认值，并精简了相关代码

Conflicts:
	contest/views.py

mq/scripts/info.py

@@ -46,10 +46,7 @@ class MessageQueue(object):
                 except User.DoesNotExist:
                     logger.warning("Submission user does not exist, submission_id: " + submission_id)
                     continue
-                if user.problems_status:
-                    problems_status = json.loads(user.problems_status)
-                else:
-                    problems_status = {}
+                problems_status = json.loads(user.problems_status)
                 problems_status[str(problem.id)] = 1
                 user.problems_status = json.dumps(problems_status)
                 user.save()