feat(php/s3/s3demo.php): verify file size after file has been sent to S3
feat(php/s3/s3demo.php): verify file size after file has been sent to S3

paul-herrmann/server-examples,FineUploader/server-examples,paul-herrmann/server-examples,paul-herrmann/server-examples,paul-herrmann/server-examples,paul-herrmann/server-examples,FineUploader/server-examples,FineUploader/server-examples,paul-herrmann/server-examples,FineUploader/server-examples,FineUploader/server-examples,FineUploader/server-examples,paul-herrmann/server-examples,paul-herrmann/server-examples,FineUploader/server-examples,FineUploader/server-examples