Import GeoLite database from pervious version when updating

[acelaya]

If for some reason more than one shlink version is released and the same GeoLite db needs to be downloaded twice in the same temp dir, an error could happen preventing it to be downloaded.

It does not happen when different GeoLite versions are downloaded, since temp paths do not match.

A way to prevent this error would be copying the old GeoLite db (in the same way the SQLite db is copied), so that the same version never needs to be downloaded more than once.