- preparation for using DI instead of requires, so we can move this out of Ghost
- have done this for both the main i18n and theme i18n file
- refactored the constructor
refs: bf0823c9a2
- continuing the work of splitting up the theme service into logical components
- this is where it starts to get fiddly as the getActive function in themeService index is required across the frontend/backend mostly due to its use in the getApiVersion method
- for now left one usage of the getActive method in place in ghost-locals middleware ready for the next phase of the refactor, which will move some of the themeService index into a shared location
