Feature/form modes access by url#29

Created by: wasabideveloper

Implementation of feature #39 (closed) .

• ran checks
• ran tests
• ran flake8
• tested views by hand:
  • /orders/new [get/post]
  • /orders/new#existing_excerpt
  • /orders/new#create_new_excerpt

@das-g, @njordan-hsr please review.