Remove the dead branch from the refquota parsing code.

"none" was a possible value without `-p`.  With `-p`, this is represented as "0".
Use the easier-to-read form.
An attempt at a test for the refquota-exceeded case.
Lint.
Lint.
Merge pull request #1018 from ClusterHQ/zfs-filesystem-size-enforced-1126

Add a functional test for the ZFS implementation of maximum volume sizes.