Fix for new download URLs after 2.1.0 release

This commit should handle the new download URLs introduced with the release of 2.1.0, it should also remain compatible with old versions.

The download server has been changed from `download.playframework.org` to `downloads.typesafe.com`.

The path has changed from `/releases/play-X.X.X.zip` to `/play/X.X.X/play-X.X.X.zip` for versions 2.1.0 and up.