Merge GetCompanySettingsController + UpdateCompanySettingsController into
CompanySettingsController with show() and update() methods.
Merge GetUserSettingsController + UpdateUserSettingsController into
UserSettingsController with show() and update() methods.
Absorb GetCompanyMailConfigurationController into
CompanyMailConfigurationController as getDefaultConfig() method.
Removes 5 single-action controllers, down to 4 Settings controllers.
