They've made two really useful modules, but they don't update api version anymore (latest is API 16). Could you manage to create the alternative modules for 24 and 26 API version?
Sorry, don't think I can. As I've stated in my post from a few months ago, I'm only able to do maintenance updates. The best I can do is poke kenzie on IRC but he's also in-and-out of the minecraft scene.
Can I use the http and/or json module to set the contents of a text file (online) to a variable?
Yes and no. To do literally what you're asking for, while possible, is regarded as inefficient for frequent updates - it's much better to set up a "RESTful" server backed by a database. If you do go this route, it'll be challenging if you're new but you'll learn a lot.
Alternatively, you can have your "database" backed by Google Sheets - I don't know much about their API but a few years ago, Farogan wrote a script to fetch data from one (but didn't manage to write one for uploading). I don't know if it still works, however. This route is probably quicker if you can figure out Google's new API.