sync-up/down uses .dockerignore. Ensure interpretation is equivalent

The sync commands use `rsync --filter=":- .dockerignore"`. It's unclear that rsync [FILTER RULES](https://linux.die.net/man/1/rsync) is equivalent to docker's [interpretation of `.dockerignore`](https://docs.docker.com/engine/reference/builder/#dockerignore-file). (It's likely it isn't).

Reconcile this