Waarp-manager should exit startup in error if some configuration value are not properly set.

• R66.DesKey should be a readable file of size 8
• R66.OutDir should be an existing writable directory
• R66.R66Cmd should be an existing and executable file
• R66.DiffusionRule should be an existing template in the database
• R66.RestSigningKey should be a readable file of size 64