Remove i18n localization adapter

[alessandro-fazzi]

Preface

This PR is part of the plan discussed in #236

• decouple light-service from I18n #238
  • preserve a basic translation functionality #238
  • do not break compatibility with existing implementations relying on I18n #238
• strip out LightService::I18n::LocalizationAdapter into its own light_service-i18n gem #239
  • require gem installation to retain full compatibility with existing implementations relying on I18n #239
• decouple light-service from ActiveSupport::Deprecation #241
  • preserve full functionality through the use of a simple custom logger built on top of Logger
• decouple light-service from ActiveSupport::Inflector
  • write a LightService::Inflector class responding only to the needed inflection methods (probably #underscore and #pluralize)
  • LightService::Inflector will delegate its capabilities to dry-inflector (which is a zero-deps gem)
• strip out LightService::Generators into its own light_service-rails gem
• release light-service 1.0
  • shut out upgrade instructions in changelog, requiring installation of new detached gems in order to retain moved functionalities (in my head this should avoid a long lasting deprecation path...but we'll have to find a place to discuss these sort of topics)
  • think about renaming the gem to light_service. This will require a well thought strategy, if desirable at all.

Details

• removed LightService::I18n::LocalizationAdapter
• removed relative specs
• removed specific I18n configuration from spec_helper
• LightService::Configuration.localization_adapter no more gets automatically updated based on i18n gem presence in bundle
• README.md updated accordingly

[alessandro-fazzi]

@adomokos @gee-forr you're welcome to review.

I'm in doubt if README's documentation should be only a link to the sidecar gem's repo (https://github.com/light-service/light_service-i18n). I can see pros and cons. Opinions more than welcome - as always.