Prevent unwanted output to the browser
Prevent unwanted output to the browser

I removed the trailing `?>` and new line that could lead to unwanted output. The end `?>` is unnecessary and discouraged (see: http://framework.zend.com/manual/1.12/en/coding-standard.php-file-formatting.html#coding-standard.php-file-formatting.general).
shield-9/php-u2flib-server,shield-9/php-u2flib-server,Yubico/php-u2flib-server,Yubico/php-u2flib-server