CompoundActivityResult inhibition_percentage can be blank

Former-commit-id: 33780e413e6e3cd5b2b8fb919eabb8fb5c85db70

ippisite/ippidb/migrations/0007_auto_20180727_0822.py

+# -*- coding: utf-8 -*-
+# Generated by Django 1.11 on 2018-07-27 08:22
+from __future__ import unicode_literals
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('ippidb', '0006_auto_20180727_0816'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='compoundactivityresult',
+            name='inhibition_percentage',
+            field=models.DecimalField(blank=True, decimal_places=0, max_digits=3, null=True, verbose_name='Inhibition percentage'),
+        ),
+    ]

ippisite/ippidb/models.py

@@ -646,7 +646,7 @@ class CompoundActivityResult(models.Model):
     activity = models.DecimalField(
         'Activity', max_digits=12, decimal_places=10)
     inhibition_percentage = models.DecimalField(
-        'Inhibition percentage', max_digits=3, decimal_places=0, null=True)
+        'Inhibition percentage', max_digits=3, decimal_places=0, null=True, blank=True)
     modulation_type = models.CharField(
         'Modulation type', max_length=1, choices=MODULATION_TYPES)