Frigg-worker

- Fix issue with looping clones

- Make sure the fetcher restarts if it crashes.
- Add stopping of preview container on error in deployment.
- Add prefixes for docker container names.

- Add modes: builder and deployer. Former main mode is now builder.
- Add support for deploying previews
- Make cloning checkout the correct commit
- Add more info to logging of clone failure
- Add hostname to job report
- Update docker-wrapper
- This fixes the issue with `CI=frigg` env variable not working

- Report pending builds, each time a task finishes
- Use click

Thanks to ekmartin