Solve Security/YAMLLoad cop

Prefer using YAML.safe_load over YAML.load.
This restricts the kind of objects that will be deserialized by YAML.load
and avoid exploits.

https://ruby-doc.org/stdlib-2.3.3/libdoc/yaml/rdoc/YAML.html#module-YAML-label-Security
http://www.benjaminfleischer.com/2013/03/20/yaml-and-security-in-ruby/