Add encrypted secrets

[paulcsmith]

Make it so that you can easily encrypt/decrypt secrets. Nice for sharing dev secrets within a team w/o committing to the repo

[matthewmcgarvey]

Rails' implementation:

https://github.com/rails/rails/blob/master/railties/lib/rails/secrets.rb https://github.com/rails/rails/blob/master/activesupport/lib/active_support/message_encryptor.rb