Get all Settings and their values. You must be a superuser or have setting permission to do this.
For non-superusers, a list of visible settings and values can be retrieved using the /api/session/properties endpoint.
Fetch a single Setting.
key value must be a non-blank string.
Update multiple Settings values. If called by a non-superuser, only user-local settings can be updated.
Create/update a Setting. If called by a non-admin, only user-local settings can be updated.
This endpoint can also be used to delete Settings by passing nil for :value.