CBQE-0: refactor conf/py-failover.conf

Change-Id: Ifb915d4a5dba7b9c3bdc2839838cf79f0cc7411a
Reviewed-on: http://review.couchbase.org/25791
Tested-by: buildbot <build@couchbase.com>
Reviewed-by: Andrei Baranouski <andrei.baranouski@gmail.com>