Implement replicaLoadBalancer boolean flag. (#38)

The flag adds a replica service with the name cluster_name-repl and
a DNS name that defaults to {cluster}-repl.{team}.{hostedzone}.

The implementation converted Service field of the cluster into a map
with one or two elements and deals with the cases when the new flag
is changed on a running cluster
(the update and the sync should create or delete the replica service).
In order to pick up master and replica service and master endpoint
when listing cluster resources.

* Update the spec when updating the cluster.

pkg/util/retryutil/retry_util.go

@@ -7,6 +7,7 @@ import (
 
 type ConditionFunc func() (bool, error)
 
+// Retry calls ConditionFunc until it returns boolean true, a timeout expires or an error occurs.
 func Retry(interval time.Duration, timeout time.Duration, f ConditionFunc) error {
 	//TODO: make the retry exponential
 	if timeout < interval {