Change caching system

[lolocomotive]

The database solution works fine right now but the new API would require a rewrite of the entire database structure and two separate parsing and serialization methods for each object (at least that's how I see it).

I think that from now on I'll just directly cache the request responses in json files (or in database entries depending on which is faster/mor practical), which will make it easier to handle.

[lolocomotive]

TODO:

• [x] Force use of cache if offline
• [x] Compare dates
• [x] Force ditch cache if user refreshed manually