Adds the ability to provide user certificates to HAProxy

[OpenStack Infra]

https://review.openstack.org/215525
commit 422a5b1e0fde667e7e9e7dd66bd3a8c6f2b9beb3
Author: Jean-Philippe Evrard <email address hidden>
Date: Fri Aug 21 11:05:07 2015 +0200

    Adds the ability to provide user certificates to HAProxy

    This change brings similar changes as this one targeting horizon:

    i.e.:
    * The server key/certificate (and optionally a CA cert) are
      distributed to all haproxy containers.

    * Two new variables have been implemented for a user-provided
      server key and certificate:
      - haproxy_user_ssl_cert: <path to cert on deployment host>
      - haproxy_user_ssl_key: <path to cert on deployment host>
      If either of these is not defined, then the missing cert/key
      will be self generated on each container. No distribution
      of the self generated certificates accross all the hosts
      is planned.

    * A new variable has been implemented for a user-provided CA
      certificate:
      - haproxy_user_ssl_ca_cert: <path to cert on deployment host>

    * The 'haproxy_cert_regen' variable has been renamed
      to 'haproxy_ssl_self_signed_regen' to have the same
      naming convention as horizon.

    * A change of certificates, whether user dropped
      or role generated, triggers pem generation and server restart

    DocImpact
    Closes-Bug: #1487380

    Change-Id: I0c88d197d8ede820ac4e0388e67a2da06b003c2b

[Major Hayden (rackerhacker)]

Fix proposed in: https://review.openstack.org/#/c/224980/