Tweak.xm - https

Uses https rather than http to pull in the json file. Reddit supports full site-wide https now, including for those json files, but doesn't yet have a full automatic redirect in place, so http://www.reddit.com/r/gaming.json for example won't automatically redirect to the SSL/TLS https://www.reddit.com/r/gaming.json. This isn't a super-major thing, but it's a nice thing to use where possible. As far as I can see this change doesn't cause any problems, but you may wish to test it yourself, etc.