Add custom SidRetrievalStrategy implementation.

This SidRetrievalStrategy behaves like the default (SidRetrievalStrategyImpl), but checks if the principal of the current authentication object is a SHOGun2 user object. In such cases, the accountName of the SHOGun2 user will be used to build a PrincipalSid.
Use SHOGun2 user object as principal of auth.

The Shogun2AuthenticationProvider will now pass the SHOGun2-User object as the principal of the authentication. The authentication provider has also been enhanced by checking if the SHOGun2 user object actually has grantedAuthorities. (The last point is a preparation as we do not yet retrieve the authorities from our SHOGun2 database).
Use custom SidRetrievalStrategy in archetype.
Minor: Using loglevel TRACE in archetype initially