Zero-downtime deploy - configurable wait time for green status

This pull request adds a --wait-time option to zdt_deploy to set the number of seconds the script waits for the environment to become green. 

The default is 600 seconds; we are using the script to deploy Docker applications, and since the docker deploy pulls large filesystem layers from a remote Docker repo, the wait time needs to be a few more minutes. This change addresses that by letting the user specify the number of seconds to wait.

One other minor change in this pull request is that the polling time for status checks is changed from 5 seconds to 10 seconds to avoid throttling errors. Without this change, we sometimes get exceptions due to throttling errors during the time the environment is installing the new Docker filesystem.