refactor(agent): Move logic from HandleEventJobOffered to MaybeBid
refactor(agent): Move logic from HandleEventJobScheduled to JobScheduled
refactor(agent): Move StopJob locking into Agent
refactor(agent): Move logic from HandleEventJobUnscheduled to JobUnscheduled
refactor(agent): unexport Agent.UnloadJob
refactor(agent): Drop Agent.Machine()
refactor(agent): unexport Agent.LoadJob
refactor(agent): unexport Agent.Bid
refactor(agent): Split JobScheduled into JobScheduledElsewhere/Locally
refactor(agent): unexport Agent.BidForPossibleJobs
refactor(agent): unexport Agent.FetchJob
fix(agent): Drop unnecessary call to VerifyJob
refactor(agent): unexport Agent.VerifyJob
refactor(agent): unexport Agent.BidForPossiblePeers
refactor(agent): unexport Agent.AbleToRun
fix(agent): Start/stop units asynchronously

Fix #466