Disable nova-baremetal-* for releases older than 2015.0
Disable nova-baremetal-* for releases older than 2015.0

Change from 2015.1 to 2015.0, as current kilo development
builds have version 2015.1.devXXX where older_than(2015.1)
returns true.

Change-Id: Ie65fc6fb72c7c3f1db1a1ed0ee2fd10878aa8de2
Closes-Bug: #1425920

stackforge/anvil,mc2014/anvil,stackforge/anvil,mc2014/anvil