Creation still in progress fixups

This should help with the recent increase in `Plines::JobBatch::CreationInStillInProgressError` errors we've been getting.  It won't cause the underlying problem causing the increase but will make it a bit less common (since 6 hours was too long of a timeout to begin with) and will log the reason the job batch creation got aborted, helping us to better understand the root cause.
https://github.com/seomoz/plines/blob/8bcdcce2d4ab7eba7ad0f6de9fe9e5e8d198697e/lib/plines/configuration.rb#L18