Rudder

It seems to be more consistent to use a full path for the directory of the policy template library than a relative one to its git repos root, even if using something else than a subdirectory of git repos root will lead to an error.

So, revert rudder.dir.relative.policyPackages to rudder.dir.policyPackages and add the necessary checks in AppConfig to ensure that rudder.dir.policyPackages is a subdirectories of rudder.dir.gitRoot