Author: Brian Barnes
MDL-48265 feedback: Added alt text to ghostscript test image
http://git.moodle.org/gw?p=moodle.git;a=commit;h=c0c96e82618bdf28aabaece693afc35a6736a9a9
http://github.com/moodle/moodle/commit/c0c96e82618bdf28aabaece693afc35a6736a9a9
+ 2.7 en [gsimage,assignfeedback_editpdf]