Right now, node logs result of every election, which makes log not only unreadable but also, in case of logging to terminal, uses surprisingly large amount of gpu to render the text alone. This PR adds a new log configuration option election_result that users can use to configure this behavior. Additionally two new stat types are added that I found very useful to track election results without resorting to staring at text log, nano::stat::detail::election_confirmed and nano::stat::detail::election_not_confirmed.