A first stab at a pull-based model for ansible. This does two things:
1. Invoke the git module via Runner to set up a git repository on the
localhost. It sets up Runner to use transport='local' and forces
the inventory to just 'localhost'.
2. Run any playbooks provided. By default, this wants to run the
playbook local.yml. This also sets transport='local' and sets
the host_list to a list: localhost, fqdn, and hostname.
The reason for setting the host_list and not using override_hosts is
because there may be plays in the playbook that are not meant for a
specific host. That is, if the git repository is for the entire site
and not host-specific, you don't want to override hosts and apply all
plays to any given host. This has the downside of potentially running a
play three times if the play is defined for 'hosts: all'.
