* Move the server daemons into their own package
With this change the internal/server package now is dedicated to the server domain (workers and controllers) and not to the server daemons.
The hope is that this will make it easier to keep the daemons decoupled from the representation of the servers in the database.
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.