It is conditional on ssl => true (line 5.)

The larger problem with this is that the download of the file will most likely fail, because the cert most likely won't match the 'localhost' name.  I did all the ssl checking here because I'm also running with the patch from #199, where you can configure Rabbit to _only_ listen on SSL.  In that case, we _must_ use https here.

Maybe an alternative would be for cases where ssl_only => true, we would still configure a non-SSL http listener for the management port, but only on localhost.  That way we can still use the http URL here, but the Rabbit service remains SSL-only from the perspective of outside of the local box.  Thoughts?