Add a remote directory without adding to the cache

[nimrand]

@jorgeorpinel

This is not such a big of a deal really. import-url will download it into the cache directly, and then link the file to the workspace (as long as it’s supported by the file system, see this doc for more info.), so there’s no duplication. -O is meant more for small files you want to track with Git or experimental files you don’t want to track at all.

Except it will then copy the corpus to the remote cache when I do a dvc push, which is what I was trying to avoid, right? Or, am I missing something?