Phase out github release system

[drweb86]

Since

Github release system is broken for month now and no support available

Migration plan.

1. Release are to be stored on synology nas web-site in JSON format similar to github release system.
2. App is ought to check for updates synology nas web-site.
3. Deployment scripts must upload release to web-site.
4. Create new maintanance release on github triggering update notification with half a year expiration, so users will switch to other update channel.
5. JS on web-site should be stupidified and always take last release, because its time consuming to update download links everywhere