Adding fillAllQueuesWithBest() to get the best rank for each queue, for a given summoner.

Due to that, I had to change how is handled the
LeagueSummonerLeagueStats in LeagueSummoner. There's some decision to
take about getting all the queues data, and not only the best. In order
to do so the Map in LeagueSummoner should be changed to a List, and the
comparison should be removed from fillAllQueuesWithBest() (and then
rename it into fillAllQueuesData()).