Add better organization/repository settings

[ajhenry]

Summary

We need a way to configure default settings for users of ICF. Taking this issue as an example: #71

We should use something like https://github.com/github/safe-settings for managing the input and behavior of these settings.

Team

Role & Responsibility	Username
DRI	@ajhenry
Engineering	@sutterj

Corresponding Work

• Investigate github/safe-settings and see what it would take to integrate
• Investigate other alternatives to safe-settings
• Add sensible defaults for the settings
• Add documentation for setting up settings

Supporting Documentation

https://github.com/github/safe-settings

https://github.com/apps/settings

[ajhenry]

After chatting with @decyjphr on the github/safe-settings project. He informed us the data format they use maps nearly one-to-one with the github REST inputs API and we should expose that format to users to set the defaults for a repo.

We are going to make the config file part of the deployment of the app. Users can then use safe-settings alongside icf if they want additional protections in their organization.