code: function Uploader( opts ) {
              this.options = $.extend( true, {}, Uploader.options, opts );
              this._init( this.options );
          }
docs: 上传入口类。
  @class Uploader
  @constructor
  @grammar new Uploader( opts ) => Uploader
  @example
  var uploader = WebUploader.Uploader({
  swf: 'path_of_swf/Uploader.swf',
  
  // 开起分片上传。
  chunked: true
  });