Add chefignore file.

* http://www.opscode.com/blog/2011/04/29/chef-0-10-preview-chefignore/
Added encrypted data bags documentation
Merge pull request #3 from mattray/encrypted_dbags

Added encrypted data bags documentation
markdown cleanup
Merge pull request #4 from mattray/encrypted_dbags

markdown cleanup
cookbooks 0.10 changes, use md for environments
Add license
Update .gitignore
Ignore .pem files and encrypted_data_bag_secret
Merge pull request #10 from sethvargo/CHEF-3942-chef-gitignore

Update .gitignore to include .chef