Verify X509 properties of trusted certificates

This should resolve https://github.com/opscode/chef/issues/1944.

I'd like to specifically request a good look at the documentation on generating certificates/self-signed certificates/subjectAltNames from @opscode/client-engineers 

@jamescott How can I leave a note for you to let me know when certain documentation has been published to the docs site?
typo: "keyUseage"