function changeYAMLValue(data, key, value) {

  data.json[key] = value;
  data.raw = data.raw.replace(new RegExp('^' + key + ':.+$', 'm'), key + ': ' + value);

}
Change a value for a specific key in YAML

- Works only with the first level keys
- Works only with keys with a single value
- Apply the changes on the json and raw

@param {Object} data  {json, raw} 
@param {String} key
@param {*}      value