Merge pull request #250 from gobuffalo/task-fixing-docker-binaries

docker: adding `latest` and  `latest-slim` tags to our docker images

task: adding latest tag

Merge pull request #248 from gobuffalo/task-fixing-docker-binaries

bugfix: fixing goreleaser binary match

bugfix: fixing goreleaser binary match

config: copying existing binary

config: copying existing binary

bugfix: correcting the docker image name again

task: correcting slim image name