Avoid throttling of cf describeStackEvents api calls (#24)
Avoid throttling of cf describeStackEvents api calls (#24)

* Avoid throttling of cf describeStackEvents api calls

Problem: Currently all events are loaded, even old once. As the event
history is long the api calls could page a few times and run into
throttling. Updating multiple stacks in parallel (e.g. on CI) can
easily cause throttling in an endless loop.

Events are loaded sorted by timestamp desc (newest events first).
So we do not need to load all of them, but can stop if we loaded an
event older than the starting time of our stack creation/update.

* Avoid initial wait interval until first checking for events

In case the stack did not need any updates, the tool waited for
'checkStackInterval' until it continues. By calling
'outputNewStackEvents' initially we avoid this unnecessary waiting.

Nordstrom/cfn