Return exit status from Wait of stopped process

This changes Wait() from returning an error whenever you call wait on a
stopped process/task to returning the exit status from the process.

This also adds the exit status to the Status() call on a process/task so
that a user can Wait(), check status, then cancel the wait to avoid
races in event handling.

Signed-off-by: Michael Crosby <crosbymichael@gmail.com>

services/tasks/service.go

@@ -227,17 +227,20 @@ func processFromContainerd(ctx context.Context, p runtime.Process) (*task.Proces
 		status = task.StatusStopped
 	case runtime.PausedStatus:
 		status = task.StatusPaused
+	case runtime.PausingStatus:
+		status = task.StatusPausing
 	default:
 		log.G(ctx).WithField("status", state.Status).Warn("unknown status")
 	}
 	return &task.Process{
-		ID:       p.ID(),
-		Pid:      state.Pid,
-		Status:   status,
-		Stdin:    state.Stdin,
-		Stdout:   state.Stdout,
-		Stderr:   state.Stderr,
-		Terminal: state.Terminal,
+		ID:         p.ID(),
+		Pid:        state.Pid,
+		Status:     status,
+		Stdin:      state.Stdin,
+		Stdout:     state.Stdout,
+		Stderr:     state.Stderr,
+		Terminal:   state.Terminal,
+		ExitStatus: state.ExitStatus,
 	}, nil
 }