Use SnakeYAML Engine to add YAML 1.2 syntax support

[ajj-stripe]

SnakeYAML Engine project reference here: https://bitbucket.org/asomov/snakeyaml-engine/src/master/

In my opinion, the YAML 1.1 => 1.2 syntax update represents a key feature of YAML parsing, given that YAML 1.2 is officially a superset of JSON

[ajj-stripe]

upon further investigation of SnakeYAML Engine

"Only JSON Schema is supported." "The Core Schema might be supported later. If anyone needs it. No one so far requested it."

This seems odd to me, but it looks like it doesn't yet support the core YAML syntax? might want to investigate using a different parser implementation for YAML 1.2, or contributing to SnakeYAML