This change removes the hard-coded credential purpose for the Credential
Libraries. It also moves the logic of creating CredentialLibraries from
CredentialSources out of the repository and into the targets.Service.
This refactor will allow for additional credential purposes to be
supported in both the service and the repository.
This moves all of the tcp target functionality into a tcp package. It
also establishes a Register function in the target package to allow
specific target types to be registered at initilazation time. When
registering, a target type needs to provide its Subtype, as well as some
RepositoryHooks that are used by the target Repository.
Timothy Messier