signv4: Strip port 80 & 443 from url (#528)
signv4: Strip port 80 & 443 from url (#528)

curl & browsers strip port 80 and 443 from host header when a user tries
to open a presigned urls, the thing that leads to a signature mismatch error.
This PR strips port 80/443 by default.
minio/minio-py,NitishT/minio-py,minio/minio-py,NitishT/minio-py