Move environment/job/product to ContainerConfig

These dimensions are necessary components of service discovery.
So, this change allows the agent to emit SD information.
Initial implementation of agent service discovery

Not yet invoked by the registry.
Scheduler registry: update for definition moves
Scheduler xf: update for definition moves
Standardize writes to disk
serviceDiscovery as interface
Prep registry for SD injection
Wire in service discovery to registry
Instrument SD invocations
glimpse:provider=harpoon
Proper hierarchy in tag order
Clarify scoping behavior in defers
Merge pull request #150 from soundcloud/agent-sd

Agent service discovery