Update Pilot Slugs on Site Settings Change

[memchk]

Currently, if you change the "Organization ICAO" in the settings page, this does not update any existing users friendly_ids. This causes URLs to be inconsistant.

Reproduce:

1. rails db:reset db:seed skyos:install
2. Fill in default user
3. Change the Organizational ICAO from "ORG" to "ABC"
4. Logbook URL will show for PID 100 "ORG100" while profile data shows "ABC100"

Screenshot:

[jvoss]

Currently the only mechanism to get the Pilot ID to regenerate the slug would be to go into user management and save each user again (even with no changes).

A hook when changing the organization ICAO will need to be written to trigger slug regeneration on each user.

This would likely need to be done in the Setting model of which functionality is provided by rails-settings-cached. Further investigation is needed to know whether all standard callbacks and change detection is available here.