Returns an aggregated object of form values.

If form fields has the same name, their value will be aggregated as an array for this given name.

@api
@returns {Object}
function getData(){
    var data = {};

    this.getFormData().forEach(function(d){
      if (Array.isArray(data[d.name])){
        data[d.name].push(d.value);
      }
      else if (data[d.name] !== undefined){
        data[d.name] = [data[d.name], d.value];
      }
      else {
        data[d.name] = d.value;
      }
    });

    return data;
  }