increase retries for cloudformation stack creation

stack creation can take a long time. The cloudformation module then returns
'CREATE_IN_PROGRESS'.

Wait 15 minutes seems reasonable. Continue only when stack is ready.

"msg": "An error occurred (ValidationError) when calling the UpdateStack operation: Stack:arn:aws:cloudformation:ap-southeast-1:719622469867:stack/ocp-ha-lab-a63d/46304ba0-a43d-11e7-ba39-500c336f388e is in CREATE_IN_PROGRESS state and can not be updated. An error occurred (ValidationError) when calling the UpdateStack operation: Stack:arn:aws:cloudformation:ap-southeast-1:719622469867:stack/ocp-ha-lab-a63d/46304ba0-a43d-11e7-ba39-500c336f388e is in CREATE_IN_PROGRESS state and can not be updated. - <class 'botocore.exceptions.ClientError'>"