Explicitly add replication pg_hba entry
Explicitly add replication pg_hba entry

If no entry was specified containing replication, we need to ensure we
add a decent entry.

As of https://github.com/zalando/patroni/commit/5ca43c1a3d578e6b7146d0ec9cc9b6f6fad4ecf0 no pg_hba entry
is automatically written for replication, therefore Spilo needs to ensure an entry exists.

zalando/spilo,zalando/spilo,zalando/spilo