Fixed some issue with the QR URL .....

[rjsoph]

Issues Addressed:

1. Added Issuer parameter to match the spec, separate from user
2. Proper encoding to handle spaces in Issuer name
3. made width and height optional parameters

Note: this may not be backward compatible given the way $domain was specified, but it does follow the Google spec located here........

https://github.com/google/google-authenticator/wiki/Key-Uri-Format

public function getUrl($issuer, $user, $secret, $width = 200, $height = 200) {
    $url =  sprintf("otpauth://totp/%s:%s?secret=%s&issuer=%s", rawurlencode($issuer), $user, $secret, rawurlencode($issuer));
    $encoder = sprintf("https://www.google.com/chart?chs=%dx%d&chld=M|0&cht=qr&chl=",$width,$height);
    $encoderURL = sprintf( "%s%s",$encoder, rawurlencode($url));

    return $encoderURL;

}