Update to ansible-1.2 and conform with playbook best practices

High level summary of changes ...

 * Updated REAMDE.md instructions
 * Add RHN registration task (only executed on RHEL)
 * Add yum_repos task to support enabling/disabling specified yum
 repositories
 * Move all files and templates into files/
 * Provide default inventory file
 * Move default variables to group_vars/all and group_vars/RedHat
 * Add handlers and move into handlers/restart_services.yml
 * Move custom rbenv bash scripts into ansible actions (tasks/rbenv.yml)
 * Renamed cfme.yml to site.yml
 * Add support to install cfme via rpm (if available)
 * Add sample beakerlib-based test driver (runtest.sh)