Fix an issue where host could be None during an instance bootup process

thus causing an error in the inventory import

awx/plugins/inventory/windows_azure.py

@@ -103,6 +103,7 @@ class AzureInventory(object):
             if len(data) > 0:
                 for host in set(reduce(lambda x, y: x + y,
                                        [i for i in data.values()])):
+                    if host is not None:
                         _meta[host] = self.get_host(host, jsonify=False)
             data['_meta'] = _meta