Add templates that allow superscript affiliations

Requires change to yaml header style

eg:
title: A Pandoc Markdown Article Example
author:
- name: Dylan Schwilk
  affiliation: 1
  email: dylan.schwilk@ttu.edu
- name: Jane Doe
  affiliation: 2
  email: jane.doe@someunversity.example.com
- name: Last Author
  affiliation: 1
  email: jane.doe@someunversity.example.com
affiliation:
    - id: 1
      address: Texas Tech University
    - id: 2
      address: Somewhere Institute of Technology
date: November 2014