core:Failed to create data center with default version

This patch fill implicitly the latest supported version as the
compatibility version of the DC when creating a new DC without
giving a specified version.

Change-Id: I158397e214db50fbf4eb753a45fcb6533ba8b97d
Bug-Url: https://bugzilla.redhat.com/show_bug.cgi?id=1053062
Signed-off-by: Eli Mesika <emesika@redhat.com>