Adds blank metadata.rb files to cookbooks missing them

Howdy,

Though I can't find an explicit requirement that ````metadata.rb```` files are required, the Opscode site says:

> Every cookbook requires a small amount of metadata. Metadata is stored in a file called metadata.rb that lives at the top of each cookbook’s directory.
> *http://docs.opscode.com/essentials_cookbook_metadata.html*

I'm using Berkshelf to model my AWS OpsWorks environments with Vagrant, and Berkshelf takes the above statement to heart and validates a cookbook by checking for the existence of the ````metadata.rb```` file.  

Seems to me that since y'all have these files in some cookbooks already, there'd be no problem adding blank ````metadata.rb```` files where they are missing.  That is what I have in this PR.  I chose to add blank versions of these files because I thought that may make it trivial for y'all to merge this.

Note that #6 discusses some of these same issues, as does #8.  Those PRs have been around a while with not much action, so I'm hoping that less code (actually *no code at all*) in this PR makes it an easier call for AWS folks.