Allow imperative to be nil

Tested by commenting out the whole `imperative` section in values-hub
and deploying MCG.

Author: mbaldessari

clustergroup/templates/imperative/job.yaml

@@ -1,6 +1,6 @@
 {{- if not (eq .Values.enabled "plumbing") }}
 {{/* Define this if needed (jobs defined */}}
-{{- if (gt (len $.Values.clusterGroup.imperative.jobs) 0) -}}
+{{- if (and $.Values.clusterGroup.imperative (gt (len $.Values.clusterGroup.imperative.jobs) 0)) -}}
 ---
 apiVersion: batch/v1
 kind: CronJob
@@ -66,4 +66,4 @@ spec:
               name: {{ $.Values.clusterGroup.imperative.valuesConfigMap }}-{{ $.Values.clusterGroup.name }}
           restartPolicy: Never
 {{- end }}
-{{- end }}
+{{- end }}