Fixed merge code populating properties from yaml.
Fixed merge code populating properties from yaml.

Fixed merge code populating properties from yaml files which was
setting only Type attribute for certain attribues related to Image
For example, default value for notcomputeImage is populated properly
in overcloud.yaml

Fixes bug #1202884

Change-Id: I9ea270dd19e9ebdb997be5d07b04ee2df28e3721

trozet/tripleo-heat-templates,openstack/tripleo-heat-templates,bcrochet/tripleo-heat-templates,trozet/opnfv-tht,redhat-openstack/tripleo-heat-templates,dprince/tripleo-heat-templates,rdo-management/tripleo-heat-templates,trozet/tripleo-heat-templates,wyg3958/tripleo-heat-templates,trozet/opnfv-tht,redhat-openstack/tripleo-heat-templates,wyg3958/tripleo-heat-templates,bcrochet/tripleo-heat-templates,bcrochet/tripleo-heat-templates,dprince/tripleo-heat-templates,openstack/tripleo-heat-templates,rdo-management/tripleo-heat-templates,trozet/opnfv-tht