Comments and whitespace changes.
Added a forced 2000ms timeout for sockets as well as HTTP connections
* Added  TileDownloaderDelegate::isTileCurrent() to check if the etag on a tile is current
* Added methods in TileWriter to support reading tags for a given tile
Broke out the isTileCurrent() and downloadTile() methods into their own try/catch blocks so that HttpHostConnection errors can be caught as an IOException. This prevents the worker pool in the ExecutorService from receiving uncaught exceptions.