added option to Inclusion tag to preserve render context and to push/pop the context.
added option to Inclusion tag to preserve render context and to push/pop the context.

philippeowagner/django-classy-tags,dongguangming/django-classy-tags,ojii/django-classy-tags,dongguangming/django-classy-tags,ojii/django-classy-tags,philippeowagner/django-classy-tags