add create and get contest list api

contest/serializers.py

@@ -0,0 +1,25 @@
+from utils.api import serializers, DateTimeTZField, UsernameSerializer
+
+from .models import ContestRuleType, Contest
+
+
+class CreateConetestSeriaizer(serializers.Serializer):
+    title = serializers.CharField(max_length=128)
+    description = serializers.CharField()
+    start_time = serializers.DateTimeField()
+    end_time = serializers.DateTimeField()
+    rule_type = serializers.ChoiceField(choices=[ContestRuleType.ACM, ContestRuleType.OI])
+    password = serializers.CharField(allow_blank=True, max_length=32)
+    visible = serializers.BooleanField()
+    real_time_rank = serializers.BooleanField()
+
+
+class ContestSerializer(serializers.ModelSerializer):
+    start_time = DateTimeTZField()
+    end_time = DateTimeTZField()
+    create_time = DateTimeTZField()
+    last_update_time = DateTimeTZField()
+    created_by = UsernameSerializer()
+
+    class Meta:
+        model = Contest