Yaml.load() return Python object may be dangerous if you receive a YAML
document from an untrusted source such as the Internet. The function
yaml.safe_load() limits this ability to simple Python objects like integers or
lists.
Reference:
https://security.openstack.org/guidelines/dg_avoid-dangerous-input-parsing-libraries.html
Change-Id: I1793ee3484f51dd663052e367d86f96f2f7598ea