Alternative monolithic repo layout from "generate repo" command

This commit proposes an alternative layout for the monolithic Chef repo generated by the 'chef generate repo' command as discussed in the community IRC meeting on Aug 20th.

Summary of Changes:

* Removed Rakefile and certificates and config dirs from recipe and generated repos
* Moved cookbook readme files into cookbook_readmes dir to facilitate using remote_directory resource
* Added 'example' cookbook
* Added example JSON role, environment and databag
* Modified READMEs to reflect examples, and link to correct Chef wiki pages
* Changed recipe to use remote_directory resource for most of the above
* Unit tests for new repo structure
We should lead by example, namespacing the attributes defined in this cookbook in an `example` namespace.