Add {{ media }} rendering in delete views

[theladyjaye]

Renders modeladmin media in delete views.

Django by default does this: https://github.com/django/django/blob/master/django/contrib/admin/templates/admin/delete_confirmation.html#L5

https://github.com/django/django/blob/master/django/contrib/admin/templates/admin/delete_selected_confirmation.html#L5

I know grappelli_safe is not necessarily supposed to follow django's templates, but adding this adding this addition allows for additional overrides on the delete_confirmation and delete_selected_confirmation views.

Grappelli proper does not add this either:

https://github.com/sehmaschine/django-grappelli/blob/master/grappelli/templates/admin/delete_selected_confirmation.html

https://github.com/sehmaschine/django-grappelli/blob/master/grappelli/templates/admin/delete_confirmation.html

As such I am unaware if there is a specific reason it does not, but I figured better to try/ask and have it be denied than not try at all.

[stephenmcd]

Looks good, thank you.