上传文件到bcs的处理器

[BcsUploaderProcessor #266](https://github.com/ecomfe/edp/issues/266)
我感觉耶没啥用，重复的太多了，那就改改吧？比如改成这样子：

```javascript
function uploadIterator( item, callback ) {
    var objectName = '/' + me.prefix + '/' + item.outputPath;
    var def = me.sdk.realUpload( item.data, me.bucket, objectName );
    def.done(function(){
        callback(null, url);
    });
    def.fail(function(){
       callback(null, null);
    });
}
```