renamed Nanoc3::Errors::GenericError to Nanoc3::Errors::Generic for consistency
renamed Nanoc3::Errors::GenericError to Nanoc3::Errors::Generic for consistency

gjtorikian/nanoc,barraq/nanoc,legallybrown/nanoc,remko/nanoc,hilohiro/nanoc,RubenVerborgh/nanoc,nanoc/nanoc