MDL-47494 copyright: fix incorrect statement

(From copy/paste error, blame Tim :P)

grade/report/grader/tests/behat/behat_gradereport_grader.php

@@ -1,5 +1,5 @@
 <?php
-// This file is part of Stack - http://stack.bham.ac.uk/
+// This file is part of Moodle - http://moodle.org/
 //
 // Stack is free software: you can redistribute it and/or modify
 // it under the terms of the GNU General Public License as published by

question/type/ddimageortext/tests/behat/behat_qtype_ddimageortext.php

@@ -1,5 +1,5 @@
 <?php
-// This file is part of Stack - http://stack.bham.ac.uk/
+// This file is part of Moodle - http://moodle.org/
 //
 // Stack is free software: you can redistribute it and/or modify
 // it under the terms of the GNU General Public License as published by

question/type/ddmarker/tests/behat/behat_qtype_ddmarker.php

@@ -1,5 +1,5 @@
 <?php
-// This file is part of Stack - http://stack.bham.ac.uk/
+// This file is part of Moodle - http://moodle.org/
 //
 // Stack is free software: you can redistribute it and/or modify
 // it under the terms of the GNU General Public License as published by

question/type/ddwtos/tests/behat/behat_qtype_ddwtos.php

@@ -1,5 +1,5 @@
 <?php
-// This file is part of Stack - http://stack.bham.ac.uk/
+// This file is part of Moodle - http://moodle.org/
 //
 // Stack is free software: you can redistribute it and/or modify
 // it under the terms of the GNU General Public License as published by

question/type/gapselect/tests/behat/behat_qtype_gapselect.php

@@ -1,5 +1,5 @@
 <?php
-// This file is part of Stack - http://stack.bham.ac.uk/
+// This file is part of Moodle - http://moodle.org/
 //
 // Stack is free software: you can redistribute it and/or modify
 // it under the terms of the GNU General Public License as published by