templatetags/page_placeholder: allow 'page' variable to be left out.
templatetags/page_placeholder: allow 'page' variable to be left out.

If it's named 'page' (very common), there is no need to repeat that.
It also makes compatibility with django-fluent-pages easier, otherwise
an additional templatetag wrapper library would have been useful.

pombredanne/django-fluent-contents,pombredanne/django-fluent-contents,django-fluent/django-fluent-contents,edoburu/django-fluent-contents,ixc/django-fluent-contents,jpotterm/django-fluent-contents,jpotterm/django-fluent-contents,django-fluent/django-fluent-contents,ixc/django-fluent-contents,jpotterm/django-fluent-contents,edoburu/django-fluent-contents,pombredanne/django-fluent-contents,django-fluent/django-fluent-contents,ixc/django-fluent-contents,edoburu/django-fluent-contents