* Consistent license message for all the go files
* Fixing the last set of unconsistencies with the license headers
* Addressing PR review comments
* Fixing busy.go and busy_test.go license header
* api4: break out license and config from system
* app: move some config functions from admin.go to config.go
* add ExperimentalSettings.RestrictSystemAdmin
* forbid various actions to restricted system admin
* update default.json
* fix function names in errors