Field Overrides: Work in Progess

We just wanted to start a place for discussion of this feature as it evolves.  

Primarily for @cpennington @carsongee @pdpinch @davisagli 
aws.py loads up static settings via json documents (one for secure and one for non-secure settings) outside of the platform repository.  This allows ops guys like @bdero and me to change platform settings without managing a fork & branch, and since it is json document loaded it makes templating the config programmatically easy via our Ansible playbooks