Policy validation generates an unhelpful error when "size" doesn't contain a unit #466
Description
What I ran:
docker volume create -d volcontiv --name $POLICY/$NAME --opt size=10
What I expected:
A helpful error message telling me that my input was not valid. It should say that the "size" must contain units (e.g., "10MB").
What I got:
An unhelpful error message: Size set to zero for non-empty CRUD backend ceph
cc: @neelimamukiri