remove JobStatus, Task abstraction and 'control status' subcommand

Control status will be replaced by job-specific output at some point.

Task was not useful anymore with state machine, may reintroduce
something similar at a later point, but consider alternatives:

- opentracing.io
- embedding everything in ctx
	- activity stack would work easily
	- log entries via proxy logger.Logger object
- progress reporting should be in status reports of individial jobs

cmd/config_job_control.go

@@ -34,10 +34,6 @@ func (j *ControlJob) JobName() string {
 
 func (j *ControlJob) JobType() JobType { return JobTypeControl }
 
-func (j *ControlJob) JobStatus(ctx context.Context) (*JobStatus, error) {
-	return &JobStatus{Tasks: nil}, nil
-}
-
 const (
 	ControlJobEndpointPProf   string = "/debug/pprof"
 	ControlJobEndpointVersion string = "/version"
@@ -76,7 +72,7 @@ func (j *ControlJob) JobStart(ctx context.Context) {
 		}}})
 	mux.Handle(ControlJobEndpointStatus,
 		requestLogger{log: log, handler: jsonResponder{func() (interface{}, error) {
-			return daemon.Status(), nil
+			panic("FIXME") // FIXME
 		}}})
 	mux.Handle("/pulljobreport",
 		requestLogger{log: log, handler: jsonResponder{func() (interface{}, error) {