Closes #198: Support for rackless devices (#902)

* Initial work to support rackless devices

* Updated device component connection forms

* Updated IP address assignment form

* Updated circuit termination form

* Formatting cleanup

* Fixed tests

netbox/dcim/migrations/0027_device_add_site.py

@@ -0,0 +1,21 @@
+# -*- coding: utf-8 -*-
+# Generated by Django 1.10.4 on 2017-02-16 21:21
+from __future__ import unicode_literals
+
+from django.db import migrations, models
+import django.db.models.deletion
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('dcim', '0026_add_rack_reservations'),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name='device',
+            name='site',
+            field=models.ForeignKey(blank=True, null=True, on_delete=django.db.models.deletion.PROTECT, related_name='devices', to='dcim.Site'),
+        ),
+    ]