some replication_manager re-factoring

- do not pass state into replication_manager:call_replicators
- use the same format for repl_type in replication_manager state and in config
  because it is way less confusing

Change-Id: I1db4bf8b7dfecfc444dafeb70237343566ee975d
Reviewed-on: http://review.couchbase.org/38119
Tested-by: Artem Stemkovski <artem@couchbase.com>
Reviewed-by: Aliaksey Artamonau <aliaksiej.artamonau@gmail.com>