CBQE-0: print progress in _wait_for_replication_to_catchup

Change-Id: Iac5f01010076c68cd3594945fefaa01891fe37ef
Reviewed-on: http://review.couchbase.org/32805
Reviewed-by: Andrei Baranouski <andrei.baranouski@gmail.com>
Tested-by: Andrei Baranouski <andrei.baranouski@gmail.com>