Use safe YAML loading method safe_load_all

Refer to kubernetes-client#719

Author: micw523

kubernetes/utils/create_from_yaml.py

@@ -53,7 +53,7 @@ def create_from_yaml(
 
     k8s_api_all = []
     with open(path.abspath(yaml_file)) as f:
-        yml_document_all = yaml.load_all(f)
+        yml_document_all = yaml.safe_load_all(f)
         # Load all documents from a single YAML file
         for yml_document in yml_document_all:
             # If it is a list type, will need to iterate its items