Added additional Chinese language tags

ECOM-5094

course_discovery/apps/ietf_language_tags/migrations/0004_add_chinese_tags.py

+# -*- coding: utf-8 -*-
+from __future__ import unicode_literals
+
+from django.db import migrations
+
+LANGTAGS = (
+    ("Chinese - Mandarin", "zh-cmn"),
+    ("Chinese - Simplified", "zh-Hans"),
+    ("Chinese - Traditional", "zh-Hant"),
+)
+
+
+def add_language_tags(apps, schema_editor):
+    LanguageTag = apps.get_model('ietf_language_tags', 'LanguageTag')
+
+    for name, code in LANGTAGS:
+        LanguageTag.objects.update_or_create(code=code, defaults={'name': name})
+
+
+def drop_language_tags(apps, schema_editor):
+    LanguageTag = apps.get_model('ietf_language_tags', 'LanguageTag')
+
+    codes = [code for __, code in LANGTAGS]
+    LanguageTag.objects.filter(code__in=codes).delete()
+
+
+class Migration(migrations.Migration):
+    dependencies = [
+        ('ietf_language_tags', '0003_fix_language_tag_names'),
+    ]
+
+    operations = [
+        migrations.RunPython(add_language_tags, drop_language_tags)
+    ]