change e testcase table UI and add CPP validator

judge/migrations/0103_fix_custom_validator.py

@@ -0,0 +1,18 @@
+# Generated by Django 2.2.9 on 2020-03-17 05:17
+
+from django.db import migrations
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('judge', '0102_fix_custom_validator'),
+    ]
+
+    operations = [
+        migrations.RenameField(
+            model_name='problemdata',
+            old_name='custom_valid',
+            new_name='custom_validator',
+        ),
+    ]