Fix httpd dir create to not error if exists
Fix httpd dir create to not error if exists

In cases where /var/log/httpd already exists, this exits with error
code 1.

$ sudo docker logs keystone-init-log
mkdir: cannot create directory '/var/log/httpd': File exists

Change-Id: I62bf08d9fc9e02d5f3016bd14bb0a090b76ac837

dprince/tripleo-heat-templates,dprince/tripleo-heat-templates,openstack/tripleo-heat-templates,openstack/tripleo-heat-templates