Created PRs and commit pushes to PRs are all already handled by `pull_request`. Having `push` without limitations causes 2 build runs on every PR commit push.
Also the `push` scenario is only required for pushes (direct or merges) to the master branch.
- Add publishing automated debian package releases via Cloudsmith.io, which allows evcc to be installed and updated via `apt`
- Add nightly docker (:latest) and deb distribution
- Disable docker builds for every commit on master
- Allow nightly builds to be triggered manually
