removeOldest() {
        const keys = this.keys();
        const keysByTimestamp = keys.map(key => ({key, timestamp: this.find(key).revisionTimestamp}));
        keysByTimestamp.sort((a, b) => a.timestamp - b.timestamp);
        this.remove(keysByTimestamp[0].key);
    }
Finds the oldest revision and removes it from localStorage to clear up space