Added support for a ruby format to knife

I'm opening this up to get some feedback on this idea. I would find great value in being able to do things like,

    knife role show my_role -Fr

and get the ruby code for configuring that role or similarly environment ([example](https://gist.github.com/bbaugher/31950ed43f0ab0eab788)). 

The main issues I see with this are,

 * Not sure if you like this idea or not and are willing to support it
 * Didn't want to add `awesome_print` to the dependency list but it was the only way I found to print a hash in a reasonable format.
 * These formatters seem to support any object while this one only supports role and environment

Also I'm working on becoming a contributor for my company, so hopefully will have that soon.