Update RabbitMQ install guide for correct ssl variable
Update RabbitMQ install guide for correct ssl variable

configure-rabbitmq.rst updated from rabbit_use_ssl to rabbitmq_use_ssl

Change-Id: I8cb3d584e7aef84264040db518e6ff0a3e2c1793
Closes-bug: #1541943

os-cloud/os-ansible-deployment,major/os-ansible-deployment,yanyao/newton,weezer/openstack-ansible,yanyao/openstack-ansible,BjoernT/openstack-ansible,BjoernT/os-ansible-deployment,openstack/openstack-ansible,bunchc/openstack-ansible,mrda/openstack-ansible,cfarquhar/openstack-ansible,Logan2211/openstack-ansible,major/os-ansible-deployment,cloudnull/os-ansible-deployment,robb-romans/openstack-ansible,major/openstack-ansible,yanyao/newton,mancdaz/openstack-ansible,major/openstack-ansible,BjoernT/os-ansible-deployment,mrda/openstack-ansible,BjoernT/openstack-ansible,weezer/openstack-ansible,yanyao/openstack-ansible,mancdaz/openstack-ansible,stackforge/os-ansible-deployment,os-cloud/os-ansible-deployment,BjoernT/os-ansible-deployment,Logan2211/openstack-ansible,cloudnull/os-ansible-deployment,robb-romans/openstack-ansible,openstack/openstack-ansible,stackforge/os-ansible-deployment,bunchc/openstack-ansible,cfarquhar/openstack-ansible,mrda/openstack-ansible