code: function(evt, callback) {
  			if($.isUndefined(evt) || !$.isFunction(callback)) {
  				return this;
  			}
  
  			var list = this.list[evt];
  			if(!list) {
  				return this;
  			}
  			var uuid = this._cbMap[callback];
  			var handlers = list.handlers;
  			var len = handlers.length;
  
  			while(len--) {
  				if(uuid === handlers[len]) {
  					handlers.splice(len, 1);
  					break;
  				}
  			}
  
  			delete this._cbMap[callback];
  
  			return this;
  		}
docs: 移出绑定事件
  @param  {String}   evt      事件名称
  @param  {Function} callback 回调函数
  @return {[type]}            [description]