Add JSON import/export capability

[dgets]

Now that the halflife timer app for mobile is coming along to a suitable state, and JSON dumping of the database is a project to be hit soon, it makes sense to implement JSON import/export here, as well. Interoperability is, after all, a goal of this project.

It'll be tricky, but I think a sync mechanism should be possible. Well, maybe not tricky to an experienced coder, but since I've never done that before it may be a bit of an operation for me. ;)