CONTRIB-4965 :: Another cast problem with Username

Signed-off-by: Joseph Rézeau <moodle@rezeau.org>
Merge branch 'MOODLE_26_STABLE' of github.com:remotelearner/moodle-mod_questionnaire into MOODLE_26_STABLE
Merge branch 'MOODLE_26_STABLE' of github.com:remotelearner/moodle-mod_questionnaire into MOODLE_26_STABLE
Merge branch 'MOODLE_26_STABLE' of github.com:remotelearner/moodle-mod_questionnaire into MOODLE_26_STABLE
Merge branch 'MOODLE_26_STABLE' of github.com:remotelearner/moodle-mod_questionnaire into MOODLE_26_STABLE
CONTRIB-5034 :: Average rank (and average values) incorrect in N/A rate questions

Signed-off-by: Joseph Rézeau <moodle@rezeau.org>