FutureBarrier implementation.

Change-Id: I415901e0ed2b4513c88b35c52953759921ce97c9
Reviewed-on: http://gerrit.aldebaran.lan:8080/9386
Reviewed-by: mnottale <mnottale@aldebaran-robotics.com>
Tested-by: fmichea <fmichea@aldebaran-robotics.com>