## Issue description
When creating a CloudFormation stack, the `CreationDate` is always `2011-05-23T15:47:44Z`

## Steps to reproduce
1. Prepare a CloudFormation file, for example
```yml
AWSTemplateFormatVersion: 2010-09-09
Description: My Stack
Resources:
  LambdaCodeBucket:
    Type: AWS::S3::Bucket
    Properties:
      BucketName: my-bucket
```
2. Create a new stack based on this file, I used the command:
```bash
awslocal cloudformation create-stack --stack-name gch --template-body file://stack.yml
```
3. List all the created stacks and confirm the `CreationDate` is not a present date
```
awslocal cloudformation list-stacks
```
```
{
    "StackSummaries": [
        {
            "StackId": "arn:aws:cloudformation:us-east-1:000000000000:stack/stack/27187f13-a645-40a0-8788-62d502358216",
            "StackName": "stack",
            "TemplateDescription": "My Stack",
            "CreationTime": "2011-05-23T15:47:44Z",
            "StackStatus": "CREATE_COMPLETE"
        }
    ]
}
```
if action == 'DescribeStackEvents':
                
                run_fix = not stack_name
                if stack_name:
                    if stack_name.startswith('arn:aws:cloudformation'):
                        run_fix = True
                        stack_name = re.sub(r'arn:aws:cloudformation:[^:]+:[^:]+:stack/([^/]+)(/.+)?',
                                            r'\1', stack_name)
                if run_fix:
                    stack_names = [stack_name] if stack_name else self._list_stack_names()
                    client = aws_stack.connect_to_service('cloudformation')
                    events = []
                    for stack_name in stack_names:
                        tmp = client.describe_stack_events(StackName=stack_name)['StackEvents'][:1]
                        events.extend(tmp)
                    events = [{'member': e} for e in events]
                    response_content = '<StackEvents>%s</StackEvents>' % obj_to_xml(events)
                    return make_response('DescribeStackEvents', response_content)
        if req_data:
            if action == 'ValidateTemplate':
                return validate_template(req_data)
            if action == 'CreateStack':
                modified_request = transform_template(req_data)
                if modified_request:
                    req_data.pop('TemplateURL', None)
                    req_data['TemplateBody'] = json.dumps(modified_request)
                    data = urlparse.urlencode(req_data, doseq=True)
                    return Request(data=data, headers=headers, method=method)
        return True
    def return_response(self, method, path, data, headers, response):