glusterfs_native pollutes user view with internal data

[Csaba Henk]

With glusterfs-native the "export location" field of shares -- which specifies for the user how they can mount the share -- occasionaly will include an user specification (like root@host:/vol). That user spec is data that is only to be used internally by the driver (for internal ssh management); the export location should come with having it stripped off. It's not harmful, but confusing for the user.

Plan: using https://blueprints.launchpad.net/manila/+spec/private-data-storage-api-for-drivers we should be able to store export location (external mount address) and user spec (internal management address) separatelly.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/224885