added Stats model

Added the lines below.  Let me know if they are okay (I didn't test yet as I don't have that setup all the way).
I think we might wanna rename this to SummonerStats (or SummonerStat? I'm undecided on the plurality) or maybe LiftetimeStats or something. There's a "RawStatsDto" for games, which I called GameStat (plurality again). Would help to avoid confusion.