Post #1332103

I fixed it by adding some heuristics to libappstream to explicitly quote something we know should be a string if it starts with a digit/punctuation (for performance reasons). I would just like to simply quote every string and be done with it (it's also more JSON-like). But keeping the more minimal style instead of changing how the emitted AppStream YAML looks like (breaking tests) was the better, more conservative fix. - For now.