Several changes

Storyboard
- removed placeholders like "summonerName" that might flash before content is loaded

SummonerVC
- temp put UIRefreshControl instead of LemonRefresh
- now calls manager to load more matches once user scrolls to last cell

SummonerManager
- when loading matches for newly registered summoner,
  all match history is fetched in 1 second intervals (avoid data limit)
  on a separate thread.
- when loading matches for not a newly registered summoner,
  first 15 matches loaded from core data whether or not they are the newest for the summoner.
- fixed loadMoreMatches fetch predicate to use oldestLoadedMatchId, not newestStoredMatchId.
  this was causing repetitive matches to show up
- when loading matches for a non-registered summoner, always fetches the next 15 from server.
  (if this is the first loading, then it will be the newest 15 matches for this summoner)