Ensure directory exists for certificates for httpd

Ensure directory exists for certificates for httpd

We used to rely on a standard directory for the certificates and keys
that are requested by certmonger. However, given the approach we plan to
take for containers that's described in the blueprint, we need to use
service-specific directories for the certs/keys, since we plan to
bind-mount these into the containers, and we don't want to bind mount
any keys/certs from other services.

Thus, we start by creating this directories if they don't exist in the
filesystem and adding the proper selinux labels.

bp tls-via-certmonger-containers

Change-Id: I0b71902358b754fa8bd7fdbb213479503c87aa46