Application: register signals only once

Change-Id: I29faf137ad42999cf3b806697e492866716cf43c
Reviewed-on: http://gerrit.aldebaran.lan/36535
Reviewed-by: mnottale <mnottale@aldebaran-robotics.com>
Reviewed-by: pdaouadi <pdaouadi@aldebaran-robotics.com>
Tested-by: pdaouadi <pdaouadi@aldebaran-robotics.com>
Application: return from run after atStop callbacks are finished

Change-Id: I69fd2fd206360e7c8148b8b95140e4ba20b7af14
Reviewed-on: http://gerrit.aldebaran.lan/36536
Reviewed-by: pdaouadi <pdaouadi@aldebaran-robotics.com>
Tested-by: pdaouadi <pdaouadi@aldebaran-robotics.com>
Merge commit 'refs/integration/team/hotfix/dev-103'