Let the upgrade work from MOODLE_25 to MOODLE_27. Thanks to Didier Raboud [OdyX]

Signed-off-by: Joseph Rézeau <moodle@rezeau.org>
CONTRIB-5199 :: Fixed upgrade problem from version 2.5 and updated build number.

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