index.js
function(option,req,res){
    this.params  = {
        'req' : req,
        'res' : res
    };
    this.option = option;
    this.features = {};//feature实例配置列表
    this.logger = Logger.getLogger();
}
function(option,req,res){
    this.params  = {
        'req' : req,
        'res' : res
    };
    this.option = option;
    this.features = {};//feature实例配置列表
    this.logger = Logger.getLogger();
}
feature flag控制类，提供接口给模板调用，判断某个feature是否开启
@param {[type]} option [description]
@param {[type]} req    [description]
@param {[type]} res    [description]