resolve(path, absolute) {
    if (!path) {
      return;
    }

    var resolved = path;
    var isAbsolute = path.indexOf("://") > -1;

    if (isAbsolute) {
      return path;
    }

    if (this.path) {
      resolved = this.path.resolve(path);
    }

    if (absolute != false && this.url) {
      resolved = this.url.resolve(resolved);
    }

    return resolved;
  }
Resolve a path to it's absolute position in the Book
@param  {string} path
@param  {boolean} [absolute] force resolving the full URL
@return {string}          the resolved path string