* Added a global config helper to easily access installation/global configs
* this will fetch the keys from cache with fallback to DB on cache miss
* ability to query multiple keys simultaneously
* interface to delete the existing global config cache
* Added tests for this new helper module
* Renamed concern from Feature to Featurable
* Feature: Installation config (#839)
* Added new model installtion config with corresponding migrations and specs
* Created an installation config yml (key value store model)
* Created a config loader module to load the installaltion configs
* Added this to the config loader seeder
* Changed the account before create hook for default feature enabling to use the feature values from installtion config
* Renamed the feature concern to Featurable to follow the naming pattern for concerns
* Added comments and specs for modules and places that deemed necessary
* Refactored config loader to reduce cognitive complexity (#839)
