Unclear error message in replication controller test

[msidana]

create_scale_and_delete_replication_controller gives unclear error message when it times out due to replicas not getting ready.
The error message is shown as this
rally.exceptions.TimeoutException: Rally tired waiting 300.00 seconds for Replication controller rally-3a609568-f4uo1550:bb0096e5-e964-405d-8c7d-5097c3209a2c to become 2 replicas running current status 2 replicas running

This looks confusing since the message indicates to become 2 replicas running current status 2 replicas running.

[msidana]

Fixed by #14