Update + test consul service + health checks for coreOS and consul 0.6

[tayzlor]

With the upgrade of consul to 0.6 we have better health check support for docker via docker + tcp checks - https://hashicorp.com/blog/consul-0-6.html#health-checks

We should be able to migrate some checks to this and we also need to ensure our checks still work with coreOS for the platform components we have.

part of this was done in #598. We still need checks for

• mesos slave
• weave
• consul agent (do we need this?)