feat(controller): make coreos the default cluster

Author: Matthew Fisher

controller/api/models.py

@@ -67,7 +67,7 @@ class Cluster(UuidAuditedModel):
 
     owner = models.ForeignKey(settings.AUTH_USER_MODEL)
     id = models.CharField(max_length=128, unique=True)
-    type = models.CharField(max_length=16, choices=CLUSTER_TYPES)
+    type = models.CharField(max_length=16, choices=CLUSTER_TYPES, default='coreos')
 
     domain = models.CharField(max_length=128)
     hosts = models.CharField(max_length=256)