[Shotwell] how to transfer/update tags in Ubuntu?

[rikona <rikona sonic net>]

Had a computer crash with Ubuntu 12.04, running Shotwell 0.12.3.
Updated to Ubuntu 14.04 using exactly the same directory structure as
in 12.04. Running Shotwell 0.18 on 14.04. I have the same photos and
photo directory structures on 14.04. 

How do I transfer the extensive tags that I had on 12.04 to the newer
version of Shotwell on 14.04? I did not see a photos.db database in
14.04. Does Shotwell 0.18 store tags in a different way? If so, is
there a way to update the older tags? It took a great deal of work to
create those tags and I'd like to not have to do that again.

Thanks,

  rikona