[WIP] Rails 4 upgrade

Just some fixes that are included for the rails 4 update at https://github.com/crowbar/barclamp-crowbar/pull/1157 for getting feedback.
For reference, this moved there: https://build.opensuse.org/package/view_file/systemsmanagement:crowbar:shared/rubygem-chef/chef-create-amqp-passwd?expand=1
(I prefer the `dd` command we have here to generate the password, btw -- if only because the password is longer)

The bit where it gets interesting is that we need to make sure we use the right package that has this new tool. I do find it wrong that the tool starts rabbitmq-server, though.