Support for configuring the rabbitmq_management web UI

When rabbitmq::admin_enable => true, then also configure RabbitMQ to enable
the rabbitmq_management web UI, running on rabbitmq::management_port.
Or, if ssl => true, then configure it as an SSL listener on
rabbitmq::ssl_management_port.

Also added a ssl_port parameter which defines the SSL port for RabbitMQ
service itself.  Previously, the rabbitmq::ssl_management_port parameter
was used for the RabbitMQ service SSL bind port.  So this potentially
breaks people who are currently using this module to configure RabbitMQ
for SSL on a non-standard port.  (They need to use the ssl_port parmeter
now, instead of ssl_management_port.)  Not exactly sure the best way
to approach a solution to that.
Is this just for puppet 2.7 compatibility? Do you really need this? 2.7 is EOL already, and the PE that uses 2.7 is EOL in one month, so I'd rather not add 2.7 code.