Add example configuration YAML file
Parse YAML config file when present, warn that .cfg is deprecated
Update docs/changelog to reflect YAML requirement
Expand template arguments from .yaml file

This allows for logically grouping commonly paired commands.  e.g.
if you have a staging environment in the DFW datacenter and a 'base'
role you can run

fix-rackspace staging-dfw base --name=web-n01.staging

to bootstrap a new node