make Ansible adapter to dump each host variables in '--list' mode

* the feature was introduced in Ansible 1.3
* to keep the old behaviour an option '--pre-1.3' is added to the
  adapter

I am not sure if this patch is up to your standards, so I'd be more than happy to accomodate any changes you'd see fit.
Yes, it is doable, and `no_meta` flag here just needs to change the default value.

I'll do it.