engine: Persist only reported supported cluster levels

In order to configure the management network on the host,
only the supported cluster levels should be persisted,
so the setup networks can identify the supported api by
the host.

Change-Id: Ifc82a6d113f1b023f2dc6950e2b3c7aad8aa9ec6
Bug-Url: https://bugzilla.redhat.com/1096757
Signed-off-by: Moti Asayag <masayag@redhat.com>