code: function FileMap(config) {
    this.config = config || {};
    this.config.exclude = config && config.exclude ? config.exclude : [];
    this.config.exclude.push('/_site');
    this.ignoreDotFiles = true;
    this.root = config.root;
    this.files = [];
    this.events = new EventEmitter();
    this.filesLeft = 0;
    this.dirsLeft = 1;
  }
docs: Initialize `FileMap` with a config object.
  
  @param {Object} options
  @api public