Adopted pattern from LogConfig to handle panic when no resource stanza at all

In testing realized that Resources night not be present at all.  Testing this case caused panic. Added in a means to collect clean defaults in that case.

api/tasks.go

@@ -186,7 +186,7 @@ func (s *Service) Canonicalize(t *Task, tg *TaskGroup, job *Job) {
 
 	s.CheckRestart.Canonicalize()
 
-	// Canonicalize CheckRestart on Checks and merge Service.CheckRestart
+	// Canonicallize CheckRestart on Checks and merge Service.CheckRestart
 	// into each check.
 	for _, c := range s.Checks {
 		c.CheckRestart.Canonicalize()
@@ -373,8 +373,13 @@ type Task struct {
 }
 
 func (t *Task) Canonicalize(tg *TaskGroup, job *Job) {
-	min := MinResources()
-	t.Resources.Canonicalize()
+	if t.Resources == nil {
+		var r Resources
+		r.Canonicalize() 
+		t.Resources = &r
+	} else {
+		t.Resources.Canonicalize()
+	}
 
 	if t.KillTimeout == nil {
 		t.KillTimeout = helper.TimeToPtr(5 * time.Second)