Use mvhs-schedule npm package for getting period for MVHS

[zphrs]

The library pulls directly from mvhs.io's backend firebase database so it is always up to date since mvhs.io's schedule is actively maintained by Mr. Nguyen. Here's the link to the repo: https://www.npmjs.com/package/mvhs-schedule

Here's a link to my periods clone that uses the npm library: https://zphyrj.github.io/mvhs-timer/
Here's the GitHub for it which you can use to figure out how to use my library: https://github.com/zphyrj/MVHSSchedule

I made the npm library with a cache which refreshes every half hour, as per Mr. Nguyen's request. It will default to the stale cache if offline.