Add rabbit driver ssl config option

The driver option is necessary as the transport_url query param
override requires the value. Default will be to use the oslomsg
rpc setting.

Change-Id: Ia3417beb195aabb10dcb24072834cb10f2827931

templates/keystone.conf.j2

@@ -21,6 +21,9 @@ log_dir = /var/log/keystone
 ## Oslo.Messaging RPC
 {% if keystone_messaging_enabled | bool %}
 transport_url = {{ keystone_oslomsg_rpc_transport }}://{% for host in keystone_oslomsg_rpc_servers.split(',') %}{{ keystone_oslomsg_rpc_userid }}:{{ keystone_oslomsg_rpc_password }}@{{ host }}:{{ keystone_oslomsg_rpc_port }}{% if not loop.last %},{% else %}/{{ keystone_oslomsg_rpc_vhost }}{% if keystone_oslomsg_rpc_use_ssl | bool %}?ssl=1{% else %}?ssl=0{% endif %}{% endif %}{% endfor %}
+
+[oslo_messaging_rabbit]
+ssl = {{ keystone_oslomsg_rpc_use_ssl }}
 {% endif %}
 
 {% if keystone_ceilometer_enabled %}