stx deploy should display more friendly message when changeset contains no changes

[talentedmrjones]

When you deploy a template that does not contain changes, deploy currently shows the full response from the AWS API, such as

{
  ChangeSetId: "arn:aws:cloudformation:us-west-2:438164822453:changeSet/stx-dpl-richardjones-e1037dfaea6a0437393c9dac9137858803b85747/3d28e64c-dc6e-4826-ba14-4e3a7148108c",
  ChangeSetName: "stx-dpl-richardjones-e1037dfaea6a0437393c9dac9137858803b85747",
  CreationTime: 2020-10-09 18:03:08.198 +0000 UTC,
  ExecutionStatus: "UNAVAILABLE",
  NotificationARNs: ["arn:aws:sns:us-west-2:012983382758:stx-notify-ccapel"],
  Parameters: [{
      ParameterKey: "MasterUserPassword",
      ParameterValue: "****"
    },{
      ParameterKey: "MasterUsername",
      ParameterValue: "****"
    }],
  RollbackConfiguration: {

  },
  StackId: "arn:aws:cloudformation:us-west-2:438164822453:stack/prod-gjp-initiatives-rds-usw2/6b3143d0-9f8c-11ea-85bb-06b7c09dad0c",
  StackName: "prod-gjp-initiatives-rds-usw2",
  Status: "FAILED",
  StatusReason: "The submitted information didn't contain changes. Submit different information to create a change set.",
  Tags: [{
      Key: "Organization",
      Value: "engineering"
    },{
      Key: "CuePath",
      Value: "/engineering/gjp/initiatives/rds"
    },{
      Key: "Environment",
      Value: "prod"
    }]
}
No changes to deploy.

All we really need to see is the No changes to deploy message.
The full API response can be sent to log.Debug instead of log.Info