refactor(agent): un-export Agent.Registry
refactor(agent): un-export Agent.Manager
refactor(agent): un-export Agent.Machine
refactor(agent): Roll ServiceTTL into MachineTTL
feat(agent): Make agent ttl configurable
refactor(agent): Change default AgentTTL to 30s
chore(agent): gofmt
Merge pull request #54 from bcwaldon/agent-ttl

Bump up Agent TTL to 30s and make it configurable