Start of the "summonerTeamService" implementation.

Added a basic implementation of the "summonerTeamService" in the usual fashion for the services. I didn't comment much, as it is exactly the same thing as the other services.

There's still a lot to do : 

    - Get all teams for a given LeagueSummoner
    - Detailed game stats given a teamId and a gameId (details of the entries of the match history)
    - Fetch the Ranking (division and league) for a given team.

I don't have the time to look into it right now, unfortunately.