Create `logger` sub-package of `config` package. Implement `LoggerSection`
type of logger sub-section. Add `Level` method to read logger level config
value. Default level is `info`.
Signed-off-by: Leonard Lyubich <leonard@nspcc.ru>
Create `config` package nearby storage node application. Implement `Config`
as a wrapper over `viper.Viper` that provides the minimum functionality
required by the application.
The constructor allows you to read the config from the file. Methods are
provided for reading subsections and values from the config tree. Helper
functions are implemented to cast a value to native Go types.
Signed-off-by: Leonard Lyubich <leonard@nspcc.ru>
