Stack Updates Wait Too Long

Vinu came by to show a deploy stuck in a backoff loop that was already over 10 backoff iterations. This was the second time I have heard this lately and all I can remember is the backoff running for 5 iterations.

I checked lib/simple_deploy/stack/status.rb and the wait_for_status method had a default count of 25! I acked wait_for_status in the rest of the code and we use the default almost everywhere.

If we aren't going to override the default, we should probably make the default something reasonable like 4-6 iterations.