Use rabbit cookbook from robert's repo for now

Let's use working version of rabbit cookbook until the following bug is fixed in upstream.
https://tickets.opscode.com/browse/COOK-4360
https://github.com/opscode-cookbooks/rabbitmq/pull/102

I set the version to '2.5.0' which doesn't exist in upstream since it's basically "v2.3.0 + another commit which was cherry-picked from newer version".