Change the default cache path

[rastersize]

We should change the default cache location the next time we release a breaking update. I think the earliest we can do that is with version 2.0 (which is a far ways off, not even planned).

Currently the path used is the temporary directory appended with a path component that is very specific.

[NSTemporaryDirectory() stringByAppendingPathComponent:@"/com.spotify.temppersistent.image.cache"];

(SPTPersistentCacheOptions.m#L51)

It would be better to set it to a more generically named path, such as:

[NSTemporaryDirectory() stringByAppendingPathComponent:@"/com.spotify.persistentcache.default"];

[8W9aG]

I'm a little worried that people will miss this when they upgrade, I wonder if there is a way to migrate the temporary paths of the cache?

[rastersize]

@8W9aG we could probably include a migrator, yeah. I guess we could try to move the old directory to the new name. Making sure we don’t overwrite anything though.

If it fails we could write a small .we-tried-to-migrate-but-if-failed-so-let-us-not-try-again file in the old directory. So we don’t get stuck in some bad loop where we try to migrate every time the app launches.