adding omit to env template

Author: wwaltersp

templates/celery_env.j2

@@ -1,4 +1,6 @@
 {{ansible_managed}}
 {% for k, v in (celeryd_default_env|combine(item.environment|default({}))).items()|sort %}
+{% if '__omit_place_holder__' not in v|string %}
 {{k}}='{{v}}'
+{% endif %}
 {% endfor %}