Update AutoRotateFilterLoader.php

Silence a warning when exif image data cannot be read that is leading to an error in symfony. 

Warning: exif_read_data(Z): Process tag(x0001=UndefinedTa): Illegal format code 0x0000, suppose BYTE in /var/www/html/vendor/liip/imagine-bundle/Liip/ImagineBundle/Imagine/Filter/Loader/AutoRotateFilterLoader.php line 19
500 Internal Server Error - ErrorException