[ELY-21] Implement the Sun variant of Unix MD5 Crypt
[ELY-4] Enhance tests for Unix MD5 Crypt
Fix algorithm names for SHA Crypt
[ELY-3] UNIX DES crypt passwords
Fix the algorithm name for Unix DES Crypt
[ELY-26] Transition the realm API to use a RealmIdentity which now encapsulates the identity specific operations.
[ELY-26] By switching to a RealmIdentity which defines an identity for a specific realm we no longer need to combine a Principal with a realm name in this way.