add encoding for configuration
write document for config.encoding
fix typo "register" -> "registers"
consider a case of "site" is unavailable in Convertible
read_yaml to accept optional parameter to override defaults
Make TestConvertible to pass with utf-8 encoding
Pass encoding parameter as string, not an object
Invoke File.read with or without options depends on Ruby version
Extract option fetch method as a separate method
Eliminating RUBY_VERSION bound construct

- Added File.read_with_options method to use
- With performance fix
Documentation update for the encoding configuration
Renaming file_read_opts_from_context to file_read_opts