Update yaml-validate.py to accept files or directories
Update yaml-validate.py to accept files or directories

For developer usage it's helpful to have the choice to provide either
an individual files, list of files, or some mix of files and directories
as you don't necessarily want to walk everything all the time.

Change-Id: I050de123bba51402a0dbb42d71e97fd27d7ce4bc

dprince/tripleo-heat-templates,dprince/tripleo-heat-templates,openstack/tripleo-heat-templates,bcrochet/tripleo-heat-templates,trozet/opnfv-tht,trozet/opnfv-tht,trozet/opnfv-tht,bcrochet/tripleo-heat-templates,bcrochet/tripleo-heat-templates,openstack/tripleo-heat-templates