Support for additional config options #55

AWS CLI seems to support other config options next to profiles. For example:

    [preview]
    cloudfront=true

(currently needed for http://docs.aws.amazon.com/cli/latest/reference/cloudfront/index.html)

I am opening this issue to discuss options for implementing this. I currently see two options: either a awscli::preview resource type, or maybe better: a general awscli::configsetting type. The latter might also be used to implement the current awscli::profile.

Any thoughts?