options.process is supported in get* but not supported in getStream

[yi]

options.process is supported in object.get but not supported in object.getStream

Although user can hack an options.subres to support process command in getSteam.

 44 
 45     options.subres = options.subres || {};
 46     options.subres['x-oss-process'] = options.process;
 48 
 49     
 50     co(function* () {
 51       var result = yield OssClient.getStream(remotePath, options);
 52       result.stream.pipe(res);
 53     }).catch(function (err) {
 54       console.log(err);
 55     });