Fix requirements

>= rather than ==

InvenTree/build/migrations/0004_auto_20180417_0657.py

@@ -0,0 +1,48 @@
+# -*- coding: utf-8 -*-
+# Generated by Django 1.11.12 on 2018-04-17 06:57
+from __future__ import unicode_literals
+
+import django.core.validators
+from django.db import migrations, models
+import django.db.models.deletion
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('part', '0019_auto_20180416_1249'),
+        ('build', '0003_build_part'),
+    ]
+
+    operations = [
+        migrations.CreateModel(
+            name='BuildOutput',
+            fields=[
+                ('id', models.AutoField(auto_created=True, primary_key=True, serialize=False, verbose_name='ID')),
+                ('quantity', models.PositiveIntegerField(default=1, help_text='Number of parts to build', validators=[django.core.validators.MinValueValidator(1)])),
+            ],
+        ),
+        migrations.RemoveField(
+            model_name='build',
+            name='part',
+        ),
+        migrations.RemoveField(
+            model_name='build',
+            name='quantity',
+        ),
+        migrations.AlterField(
+            model_name='build',
+            name='status',
+            field=models.PositiveIntegerField(choices=[(40, 'Cancelled'), (10, 'Pending'), (20, 'Allocated'), (50, 'Complete'), (30, 'Holding')], default=10, validators=[django.core.validators.MinValueValidator(0)]),
+        ),
+        migrations.AddField(
+            model_name='buildoutput',
+            name='build',
+            field=models.ForeignKey(on_delete=django.db.models.deletion.CASCADE, related_name='outputs', to='build.Build'),
+        ),
+        migrations.AddField(
+            model_name='buildoutput',
+            name='part',
+            field=models.ForeignKey(on_delete=django.db.models.deletion.CASCADE, related_name='builds', to='part.Part'),
+        ),
+    ]