added unit test for create vacancy

finished implementing validation feature

core/migrations/0032_merge_20191008_1618.py

+# -*- coding: utf-8 -*-
+# Generated by Django 1.10.5 on 2019-10-08 09:18
+from __future__ import unicode_literals
+
+from django.db import migrations
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('core', '0029_merge_20191008_1247'),
+        ('core', '0031_auto_20191008_1608'),
+    ]
+
+    operations = [
+    ]