improved docker / container support

Issue #705

• [x] allow to disable auto update -> added update_rs(..., $mode = 'default') possible to set from environment variable for none/major/minor/patch, if variable isn't set same behavior as before
  • [ ] fix explicit version checks
• [x] create dbconfig if not exists in php
  • [ ] add migration from old other/dbconfig.php -> config/db.php
• [ ] worker.php status checks for
  • [x] process running
  • [ ] ts3 connection successful
  • [ ] last update successful
• [ ] all changes tested

1. Iam not experienced in PHP so a review before removing WIP is mandatory in my opinion.
2. Is there an prefered testing method?
3. Do you prefer a two step pr? E.g. first for changes needed in preparation but without Dockerfile?