code: function doesLaunchConfigurationExist (autoScaling, launchConfigurationName) {
    return autoScaling.
      describeLaunchConfigurationsPromised({
        LaunchConfigurationNames: [ launchConfigurationName ]
      })
      .then(function found (data) {
        return !_.isEmpty(data.LaunchConfigurations)
      })
  }
docs: Uses AutoScaling.describeLaunchConfigurations to check existence of the
  launch configuration. If the list of LaunchConfigurations returned is empty
  doesLaunchConfigurationExist is resolved as False, if it's not empty it is
  resolved as True.
  
  @param autoScaling
  @param launchConfigurationName
  
  @returns {Promise}