fix typo

lib/transports/s3/remote.js

 
   var s3Options = { params: { Bucket: bucket } };
   if (process.env.S3_ENDPOINT) {
-    S3Options.endpoint = process.env.S3_ENDPOINT;
+    s3Options.endpoint = process.env.S3_ENDPOINT;
   }
   var s3 = new AWS.S3(s3Options);