Update database not working in some cases due to ClassCastException

[Sloy]

http://crashes.to/s/ea704e2d0bb

It's a non-fatal issue, but it's preventing some users from updating their database.
Seems like I forgot to test what happens when you already had a database version in preferences. I changed the preference from int to long, and it breaks in this one case.

As we say in Spanish, "qué huevos, macho".