Read datacube information from pillar

Summary:
The new datacubes pillar entry will allow to add arguments,
like the user for the directory or the ZFS volume.

Ref T1537

Test Plan: Deploy on WindRiver, should be no-op

Reviewers: dereckson

Reviewed By: dereckson

Maniphest Tasks: T1537

Differential Revision: https://devcentral.nasqueron.org/D3087