PeriodicTask: add forward
PeriodicTask: add forward

Change-Id: I25455cef7688bffef83c09c4f60e578259c655c3
Reviewed-on: http://gerrit.aldebaran.lan/62299
Reviewed-by: vpaleologue <cb19838a79eb484e12a6960acfbf7c16dfdb80d9@aldebaran-robotics.com>
Reviewed-by: jlamotte <70353e7b0c7d18b7fc75605daf0ccba69fcd3222@aldebaran.com>
Tested-by: pdaouadi <fc1eb3334d3fdad315bae23aa166bc70bd434067@aldebaran-robotics.com>

aldebaran/libqi,aldebaran/libqi,aldebaran/libqi