Rename qrcode.php to QRcode.php

Get rid of the error message in Symfony2 (dev)

Case mismatch between loaded and declared class names: BG\BarcodeBundle\Util\Plugins\qrcode vs BG\BarcodeBundle\Util\Plugins\QRcode
Rename datamatrix.php to Datamatrix.php
Merge pull request #1 from wodka/patch-1

Rename qrcode.php to QRcode.php