Changed default_cluster_ips property to also include arbitrator IP
Changed default_cluster_ips property to also include arbitrator IP

- Now default cluster IPs potentially include all 4 IPs (3 mysql nodes plus
    arbitrator, unless any are nil)

[#110772724]

Signed-off-by: Ben Calegari <9a58dcb4629f0f5a554e5de501c7fc8e7b1788bc@pivotal.io>

cloudfoundry/cf-mysql-release,cloudfoundry/cf-mysql-release,cloudfoundry/cf-mysql-release,cloudfoundry/cf-mysql-release