"make check" command use cppunit and "sipp" for our tests framework.
Add them to our current validation docker file.
Also fix Acquire::Retries option (typo).

Change-Id: I92a1ad0b5aa3a8066c48445261ff38e4e5a01061
Reviewed-by: Olivier Soldano <olivier.soldano@savoirfairelinux.com>