Add the optional header image to all pages

opentech/forms/migrations/0002_formpage_header_image.py

opentech/forms/models.py

opentech/home/migrations/0003_homepage_header_image.py

opentech/home/models.py

opentech/news/migrations/0002_add_header_image.py

opentech/news/models.py

opentech/people/migrations/0002_add_header_image.py

opentech/people/models.py

opentech/standardpages/migrations/0002_add_header_image.py

opentech/standardpages/models.py

opentech/templates/base.html

opentech/utils/models.py