Adds functionality to allow chef_command to be specified in group configurations
Releases version 1.3.0 of Rivet.
Bumps version to 1.4.0 for release

- Adds functionality to apply an elastic_ip durning bootstrap
- Adds functionality to apply knife commands for a specified
  chef_username durning bootstrap
- Tweaked some of the code styling to adhere to common Ruby styling
  conventions