Deployment User Setup

The `continuous_integration.rb` now uses the Travis CLI tool to generate SSH keys for the deployment user.
@vandahm okay.  but the problem still exists that you need to ensure they are logged in before executing any of the commands, IMO it's more straightforward to just have them reuse the same credentials for both commands (and logout afterwards) than to try and explain "log in w/ personal account first and then enter deployer password afterwards)".