refs #9178, refs https://github.com/TryGhost/Ghost/pull/8980
refs #9178 - avoid importing 4 modules (logging, errors, events and i18n) - simply require common in each file
refs #9178
refs #9178 - Introduce the /services/ folder - Move xmlrpc there - Move slack there - In slack: remove a usage of the settings API that should use settingsCache - In slack: Simplify the tests - Various tiny changes to move towards code consistency