Avoid a race condition in the replication test module

Avoid a race condition in the replication test module when checking
for site IP addresses in the replication status output.  The test
waits for a connection on the leader, but it only queries the
replication status to check for the expected site IP addresses a
single time. Change the test to wait and re-check the status output to
give greater assurance that if the expected site IP addresses are not
present it is due to legitimate failure and not a race condition in
checking the replication status. This change affects the replication
and replication_upgrade tests as well as any other tests that call the
replication:replication function.
Merge pull request #655 from basho/bugfix/replication-verify-site-ip-race

Avoid a race condition in the replication test module