webadmin: New cluster dialog does not reflect data center compatibility version

The default compatibility version of the cluster is not the same as the
DC one when creating a cluster via webadmin using the 'New DC Guide Me'.

Change-Id: I52e189cb2a779edfdc87f8c3d58b8d703975ecf9
Bug-Url: https://bugzilla.redhat.com/1082321
Signed-off-by: Ravi Nori <rnori@redhat.com>