the coordinates of SVInfiniteScrollingView

Sometimes SVPullToRefreshView and SVInfiniteScrollingView exist. So fix
the coordinates of SVInfiniteScrollingView。
Sometimes SVPullToRefreshView and SVInfiniteScrollingView exist. So fix
the coordinates of SVInfiniteScrollingView。
Fixed iOS7 warnings for sizeWithFont
Thinner arrow to match iOS 7 style.