concatFiles(tree, options) {
    options.sourceMapConfig = this.app.options.sourcemaps;
    return require('broccoli-concat')(tree, options);
  }
Shorthand method for [broccoli-concat](https://github.com/ember-cli/broccoli-concat)

    @private
    @method concatFiles
    @param {tree} tree Tree of files
    @param {Object} options Options for broccoli-concat
    @return {tree} Modified tree