Allow more time for API requests to be completed

We currently poll for success, but physical machines can take a while
to respond to IPMI etc. The current defaults reliably fail to complete
with 5 workers (which is the desired default). Until we have event
based logic from Ironic -> Nova we need to try harder, or be
unreliable. 60 retries of 2 seconds each means 2 minutes before a
truely hard fail (as opposed to queue backlog) is reported. Note that
deploys can starve deletes at the moment, so this fix is not enough to
stop spurious reports of problems.

Change-Id: I917a4430e5e77936deb82343ff057b9adc9822ec
Partial-Bug: #1319858
Merge "Allow more time for API requests to be completed"