Add 'keywords' field to Part

- Shows up in search results

InvenTree/part/migrations/0023_part_keywords.py

@@ -0,0 +1,18 @@
+# Generated by Django 2.2 on 2019-05-14 07:15
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('part', '0022_auto_20190512_1246'),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name='part',
+            name='keywords',
+            field=models.CharField(blank=True, help_text='Part keywords to improve visibility in search results', max_length=250),
+        ),
+    ]