Cloudformation doesn't work with stacks in ROLLBACK_COMPLETE state

```
An error occurred (ValidationError) when calling the UpdateStack operation: Stack:arn:aws:cloudformation:us-east-1:xxxxx:stack/yyyyyyyy/zzzzzzzz is in ROLLBACK_COMPLETE state and can not be updated.
388
```

I think this is because https://github.com/bitovi/bitops/blob/master/scripts/cloudformation/cloudformation_deploy.sh#L26 simply checks if the stack exists to decide whether to do a `create` or `update` action. This check needs to be enhanced to also consider the state of the stack.

A potentially helpful resource
https://stackoverflow.com/questions/57932734/validationerror-stackarn-aws-cloudformation-stack-is-in-rollback-complete-state