Add option to change when the signed upload URL expires

Author: techwes

README.md

@@ -118,6 +118,7 @@ app.use('/s3', require('react-s3-uploader/s3router')({
     bucket: "MyS3Bucket",
     region: 'us-east-1', //optional
     signatureVersion: 'v4', //optional (use for some amazon regions: frankfurt and others)
+    signatureExpires: 60, //optional, number of seconds the upload signed URL should be valid for (defaults to 60)
     headers: {'Access-Control-Allow-Origin': '*'}, // optional
     ACL: 'private', // this is default
     uniquePrefix: true // (4.0.2 and above) default is true, setting the attribute to false preserves the original filename in S3

s3router.js

@@ -90,7 +90,7 @@ function S3Router(options, middleware) {
         var params = {
             Bucket: S3_BUCKET,
             Key: fileKey,
-            Expires: 60,
+            Expires: options.signatureExpires || 60,
             ContentType: mimeType,
             ACL: options.ACL || 'private'
         };