Supports changing tile size from default 256x256

[Joohansson]

Will allow changing tileSize from swift code and also set correct size in JCTiledLayer (or tiles will have wrong resolution on the phone). Tested with 512x512 tiles

Use like this: let scrollView = JCTiledScrollView(frame: self.view.frame, contentSize: imageSize) scrollView.tiledView.tileSize = CGSize(width: CGFloat(256.0), height: CGFloat(256.0))