I added this because there's a need for id (primary key) column in https://github.com/ugisozols/awesome_nested_set/blob/6dcbb67bedff9edd72449191ee2144802f528639/lib/awesome_nested_set/model/validatable.rb#L21. Maybe there's more elegant way of getting id column with existing code? Should this be made configurable like the rest of the column names?