Require the 'name' attribute is present in `metadata.rb`

@fnichol after tracing all day, I found this.

If there's no `name` attribute in the `metadata.rb`, TK fails to copy the cookbooks, but it doesn't fail until later up the stack.

So I inserted a check... and it **still** doesn't fail until later up the stack, but the exception is definitely raised. I think we need to link the supervisor/actors together and listen for exceptions on the children?

Basically, I want to give the user a happy little error say "PUT A NAME ATTRIBUTE IF YOUR FREAKING COOKBOOK", but nicer :smile:. And instead I get "Message: Failed to complete #converge action: [can't convert nil into String]"

:warning: not ready for merge