Client doesn't order ketama nodes properly

Because $HOST is not replaced in the config until a later processing stage has taken place, the ketama continuum needs to be updated after substitution is applied. This is also due to the library still lexically sorting node entries, wherein "$HOST" is used as the key, rather than the node itself.

A current workaround to be implemented is to re-sort the continuum entries whenever the host string is updated/replaced...