lib/classes/Variables.js/Variables/populateVariables
class Variables:  populateVariables(properties) {
    const variables = properties.filter(property =>
      _.isString(property.value) &&
      property.value.match(this.variableSyntax));
    return _.map(variables,
      variable => this.populateValue(variable.value, false)
        .then(populated => _.assign({}, variable, { populated })));
  }