Autoupdates

[jakobharder]

or have at least a manual button to check

[taubenangriff]

The app should support updates from any github repo.

• [ ] Remember from which repository and when the the mod was installed
• [ ] Being able to check for an update, based on the timestamp of the new release
• [ ] Being able to queue the update
• [ ] Check for updates at app start

Keep in mind #102 for this.