rabbitmq_management block is created twice.
rabbitmq_management block is created twice.

Following this commit 8f75ff5cfea7945a0d6a4074184a7279a81349d4, if one
use this simple manifest:

```puppet
class { 'rabbitmq':
    admin_enable   => true,
    service_manage => true,
}
```

Then two blocks of

```
{rabbitmq_management, [
]}
```

gets created.

The problem is that only the parameters of the first block is taken into
account.

Furthermore the /first/ block is *always* created.  The template has:

```
+<% if @config_management_variables -%>,
+  {rabbitmq_management, [
+    <%= @config_management_variables.sort.map{|k,v| "{#{k}, #{v}}"}.join(",\n    ") %>
+  ]}
+<%- end -%>
```

and config_management_variables is set to `{}` with is not `false`.

This is an attempt to fix this and keep the same behavior.

cegeka/puppet-rabbitmq,cegeka/puppet-rabbitmq