add judge config languages and problem tag api

problem/tests.py

@@ -0,0 +1,12 @@
+from utils.api.tests import APITestCase
+
+from .models import ProblemTag
+
+
+class ProblemTagListAPITest(APITestCase):
+    def test_get_tag_list(self):
+        ProblemTag.objects.create(name="name1")
+        ProblemTag.objects.create(name="name2")
+        resp = self.client.get(self.reverse("problem_tag_list_api"))
+        self.assertSuccess(resp)
+        self.assertEqual(resp.data["data"], ["name1", "name2"])

problem/urls/oj.py

@@ -0,0 +1,7 @@
+from django.conf.urls import url
+
+from ..views import ProblemTagAPI
+
+urlpatterns = [
+    url(r"^tags$", ProblemTagAPI.as_view(), name="problem_tag_list_api")
+]

problem/views.py

@@ -0,0 +1,8 @@
+from utils.api import APIView
+
+from .models import ProblemTag
+
+
+class ProblemTagAPI(APIView):
+    def get(self, request):
+        return self.success([item.name for item in ProblemTag.objects.all().order_by("id")])