Fix missing volume_name_template flag.

volume_template_name was converted to a self.configuration option,
however we don't import that opt in the self.configuration changes.

This patch switches the specifier back to the global CONF

Fixes bug: 1199909

Change-Id: I1431ba8a46b3a86ed77c02646a1c5fd1f62ae010
Merge "Fix missing volume_name_template flag."