Prevent an array index exception if server does not have an image.

Change-Id: I63d3a92cea4da042942540b0800b5c4e825983c5
Fixes: bug #1202784

openstack_dashboard/api/nova.py

@@ -85,6 +85,8 @@ class Server(APIResourceWrapper):
     def image_name(self):
         import glanceclient.exc as glance_exceptions
         from openstack_dashboard.api import glance
+        if not self.image:
+            return "(not found)"
         try:
             image = glance.image_get(self.request, self.image['id'])
             return image.name