Refactor List, Next and Remainder into `simple_tag`. Django 1.4+

simple_tag() cannot handle filters in Django 1.3 so this causes 3 tests to fail. In reality though, the only scenario effected is `{% render_list list_var|filter %}`. That *previously* worked whereas filtering the template arguments to List/Next/Remainder never worked. (It was fixed in ebe183dc466cac52eb58c00f97bc28996f65ed15 but that was never in a public release.)
Acknowledge and silence the three expected failures introduced to Django 1.3 in the `simple_tag` refactor.
Merge branch 'simple_tag_refactor' into v1.3.0-prep

* simple_tag_refactor:
  Acknowledge and silence the three expected failures introduced to Django 1.3 in the `simple_tag` refactor.
  Refactor List, Next and Remainder into `simple_tag`. Django 1.4+

Conflicts:
	armstrong/core/arm_layout/tests/templatetags/layout_helpers.py